Is it a copyright-protected (DRM) file? Copyright-protected files cannot be played.
Also, the file may be corrupted, the file name was changed, or the file was moved. Check the status icon in the library.
For details, refer to “Managing music files” in “rekordbox software manual”. Obtain “rekordbox software manual” from the rekordbox web site.
http://rekordbox.com

Check the following:

1. Is the [MASTER LEVEL] control set to the proper position? Adjust the [MASTER LEVEL] control according to the connecting device.
2. Is the [HEADPHONES LEVEL] control set to the proper
position? Adjust the [HEADPHONES LEVEL] control according to the connecting device.
3. Is the [TRIM] control set to the proper position? Adjust the [TRIM] control so that the channel level indicator’s orange indicator lights at the peak level.

It is possible that the language of the song information is not supported by the connected DJ software. For information on languages supported by the DJ software, see your DJ software's operating instructions.

Since MP3 and ACC format files support ID3 tags used to embed song information, the artist names and album names can be read and displayed from the files. On the other hand, WAV and AIFF files do not support the ID3 tag, thus artist names and album names cannot be read and displayed from the files. To display song information, you must use the Edit item to edit the song information. With the Import from iTunes function, since the file information held by the iTunes library is referenced, song information is displayed even when included as part of WAV or AIFF files.

When the master tempo mode is turned on, key control processing is performed to keep the key constant, so the sound quality changes. This change in sound quality is normal considering the product’s specifications; it is not a malfunction.

Is the crossfader curve setting appropriate?
The crossfader curve setting can be changed in [Preferences] of rekordbox. For details, see rekordbox Operating Instructions.
rekordbox Operating Instructions can be checked on the support site of the rekordbox product site.

Also, the crossfader cut lag can be adjusted to any of 53 levels in [Preferences] of rekordbox. For details, see this unit’s Operating Instructions. The Operating Instructions can be checked on the support page.

Check the following.
(1) Is the jog dial dirty?
　　An electrostatic system is used as the detection method in the jog dial of this unit.
　　Therefore, if the jog dial is dirty or the user has hand cream on their hands, it may not respond.
　　When cleaning the jog dial, wipe it with a dry soft cloth.
　　If it is very dirty, prepare a 5:1 or 6:1 solution of water and neutral detergent, immerse a soft cloth in the solution and wring it out well, wipe off the dirt with the cloth, and then wipe the jog dial with a dry cloth.

(2) Does the jog dial respond when touched while touching some other metal part of the unit?
　- If the jog dial does not respond to touching, the unit may be malfunctioning
　　　　If the jog dial responds to touching, the unit may be affected by a connected device.

　- The jog dial’s touch sensor may not work properly depending on the computer (e.g., a BTO computer) or amplifier connected to the unit or the connection environment (ground connection status, etc.) of that device.

Is crossfader assignment set properly?
Crossfader assignment can be set for each deck in rekordbox.
For details, refer to “Mixer” in rekordbox Operating Instructions. rekordbox Operating Instructions can be checked on the rekordbox product site.
http://rekordbox.com

Is the microphone talk over function on, and is a microphone that is on and connected to this unit placed near a speaker?
When the microphone picks up the speaker sound, the talk over function is activated and makes the output sound smaller unexpectedly. Turn off the talk over function or the microphone, or use the microphone away from speakers.

The talk over function may be accidentally activated due to the influence of static electricity, etc. If you do not want to use the talk over function, turn it off.
The microphone talk over function setting can be changed in [Preferences] of rekordbox. For details, see this unit’s Operating Instructions.
The Operating Instructions can be checked on the support page.

Is the included USB properly connected?
This unit may not operate properly due to static electricity or other external influences. In this case, proper operation may be restored by turning the power off, then turning
the power back on.

When the unit is connected to a computer (Windows) for the first time or when it is connected to a different USB port on the computer, the message "Installing device driver software" may appear on the computer screen. Wait until the message "Your devices are ready to use." message appears.

-In the middle of installation, the message "Connect to Windows Update to search for hardware? ] message may appear. In that case, select [No, not this time] and then click [Next] to continue installation.
-In the middle of installation, the message "Choose the installation method" may appear. In that case, select "Install software automatically (recommended)" and then click "Next" to continue installation.
-In the middle of installation, the [Windows Security] screen may appear. In that case, select "Install this driver software." to continue installation.

For Windows
Check that “DDJ-RB” is displayed in the “Sound, video and game controllers” item in Device Manager.
If “?” or “!” is displayed, try the following procedure.

1. Right-click the item where “?” or “!” is displayed, and then click [Uninstall].

2. The uninstall confirmation dialog box appears. Click OK to perform the uninstallation.
If “DDJ-RB” is displayed in the “Sound, video and game controllers” item as well, also uninstall it using the same procedure.

3. Disconnect this unit from the USB port of the PC.
　　Do not connect the unit via USB until the driver software is reinstalled.

4. Uninstall the driver software and restart the PC.

5. Reinstall the driver software and then connect the unit.

For Mac
The driver software may not have been installed properly.
Disconnect the USB cable and uninstall the driver software.
The computer is restarted. Once it has been restarted, install the driver software again.

From the Control Panel, check that the account type in "User Account" is "Computer Administrator". You cannot install the device software if it is not "Computer Administrator".

The firmware update is probably not finished. Turn off the power, enter the update mode again, and then perform the update.
For details on the procedure, download the update guide from the firmware download page.

When the [Back spin length] setting in [Preferences] of rekordbox is set to [Short] or [Long], the behavior may be as if the jog dial continues to be rotated even after it has stopped being rotated due to software processing. To match the playback position to the actual rotation state of the jog dial, set the [Back spin length] setting to [Normal].
The procedure to set the [Back spin length] setting to [Short] is as follows.
1) Connect this unit to your computer via a USB cable.
2) Change the [Back spin length] setting in [Preferences] > [Controllers] > [Decks] of rekordbox to [Short].

Deck 1 and deck 2 of rekordbox dj are supported by this unit. Deck 3 and deck 4 can be operated on the computer or by connecting a separate general MIDI controller.
To operate rekordbox dj with other than this unit, use the MIDI assignment function of rekordbox dj.
For information regarding the MIDI assignment function of rekordbox dj, refer to “MIDI LEARN Function Operation Guide.”
http://rekordbox.com

1. Is the included USB properly connected?
Connect the included USB cable properly.
2. Is the supply enough from the USB terminal on your computer connected to this unit?
Connect to the USB terminal which can supplies enough.
If other devices which is not used for DJ play is connected to your computer, disconnect them.
Do not use your computer running on its battery. Supply power to the computer from an AC power supply.

This unit may not operate properly due to static electricity or other external influences. In this case, proper operation may be restored by turning the power off, then turning the power back on.

If this unit operates abnormally or does not start, disconnect the USB cable, wait a while, and then start the unit again.
If the symptoms still occur, put in a request for repairs.

Check the following.

1. Is the driver software installed?

　For details on the installation procedure, check the Operating Instructions.
　The driver software and Operating Instructions can be downloaded from the support page.
　　Driver software
　　Operating Instructions

2. Is your computer recognizing the unit?
Check that the firmware version of this unit is displayed with the following procedure.
- Mac OS: Open the Apple menu while pressing the [option] key and then select [System Profiler...] > [Hardware] > [USB].
- Windows 10: Click the Start button > [All apps] > [Pioneer] > [DDJ_RB] > [DDJ_RB Setting Utility].
- Windows 8.1: Click [Apps View] > [Pioneer] > [DDJ_RB] > [DDJ_RB Setting Utility].
- Windows 7: Click the [Start] menu > [All Programs] > [Pioneer] > [DDJ_RB] > [DDJ_RB Setting Utility].

3. Is the USB cable connected properly?
　⇒ Connect this unit and the computer directly using the included USB cable.

4. Are you using a USB hub?
　⇒ A USB hub cannot be used. Be sure to connect this unit to a USB port on the computer that can supply power.

5. Are other applications running?
　Exit all other applications including the screen saver and resident software.
　(When exiting antivirus and other security software, before doing so, disable the Internet connection to ensure the security of your computer.)

6. Are USB devices other than this unit connected?
　Remove external hard disks and the keyboard (for some models), etc. to check the status with only the built-in hard disk.

7. If your computer has more than one USB port, check using a different USB port.

8. Are multiple ASIO drivers for units other than this unit installed on the computer? Uninstall unnecessary ASIO drivers. For details on how to uninstall an ASIO driver, check with the manufacturer of the respective ASIO driver.

9. Check the sound settings on the computer.
[Windows]
Set the sound settings again.
(1) Connect the unit to the computer and turn on the power.
　　Go to [Control Panel] > [Hardware and Sound] and click [Sound].

(2) If DDJ-RB is indicated as "Default Device," proceed to (3).

(3) Click a sound device other than DDJ-RB and click the [Set Default] button.
Then, click the [OK] button to close the window.

(4) Close the Control Panel and restart the computer.

[Mac]
Reload the Audio MIDI settings.
(1) Connect the unit to the computer and turn on the power.
(2) Open the [Applications] folder, [Utilities] folder, and [Audio MIDI Setup.app].
(3) The [Audio Devices] window appears.
Confirm that [Audio MIDI Setup] is displayed on menu bar (application menus) and then click [Window].
Select [Show MIDI Studio] or [Show MIDI Window]. (The displayed name depends on OS version.)

(4) The [MIDI Studio] window appears. Click the [DDJ-RB] icon once so that it turns blue.
When the icon turns blue, click [Remove Device].
The [DDJ-RB] icon disappears and then reappears after a short while.

(5) Exit [Audio MIDI Setup] and turn off the power of the unit.
(6) Turn on the power of the unit and then launch the DJ software.

There are various possible causes. Check the following.

(1) Are the connection cables connected properly? Connect the connection cables properly. For details, see “Connections” in the Operating Instructions.
(2) Are terminals or plugs dirty? Wipe any dirt off terminals and plugs before making connections.
(3) Are the connected powered speakers, etc., set properly?
Set the external input selector and volume of the powered speakers, etc. properly.
(4) Is the driver software set properly? Set the driver properly. For details, refer to “Preparing rekordbox” in the Operating Instructions.

(5) Check the procedure to output audio.
[Outputting audio]

The following describes the procedure for outputting the channel 1 sound as an example.

　Output audio from the [MASTER] output terminals.
　Set the volume of the device connected to the [MASTER] output terminals (power amplifier, powered speakers, etc.) to an appropriate level. Note that the output sound may be loud if the volume is set too high.

　1. Set the positions of the controls, etc., as shown below.
　[MASTER LEVEL]: Turned fully counterclockwise
　[TRIM]: Turned fully counterclockwise
　[EQ (HI/MID/LOW)]: Center
　[FILTER]: Center
　[Channel fader]: Moved towards you

　2. Play the track.
　3. Move the channel fader ([Image No. 76] Figure 7) backward.
　4. Turn the [TRIM] control ([Image No. 76] Figure 2).
　　Adjust [TRIM] so that the orange indicator on the channel level indicator lights at the peak level.
　5. Turn the [MASTER LEVEL] control ([Image No. 76] Figure 9) to adjust the speaker audio level.

　Output audio from the headphones.
　1. Set the positions of the controls as shown below.
　[HEADPHONE LEVEL]: Turned fully counterclockwise

　2. Press the headphones [CUE] button of channel 1.
　3. Turn the [HEADPHONE LEVEL] control ([Image No. 76] Figure 17).
　　Adjust the sound level output from the headphones to an appropriate level.

1. Are you using softwares other than rekordbox at the same time?
Quit other applications to decrease the load on the computer.
If operation continues to be unstable, try disabling the wireless network or other wireless connections, antivirus software, the screen saver, the low power mode, etc.
2. When other USB devices are connected to the computer.
Disconnect other USB devices from the computer.
When another USB audio device is connected to the computer at the same time, it may not operate or be recognized normally.
3. Are you using a USB hub? USB hubs cannot be used. Connect the computer and this unit directly using the included USB cable.
4. There is a problem with the USB port to which this unit is connected.
If your computer has multiple USB ports, try connecting this unit to a different USB port.
5. Is this unit connected to a notebook computer running on its battery?
Supply power to the notebook computer from an AC power supply.
(Depending on the notebook computer’s settings, the low power mode may be set when the computer is running on its battery, automatically reducing the performance of the computer itself.)

Is a cue set?
Set the cue.

1. Is rekordbox set to the [EXPORT] mode?
Click the area indicated by [EXPORT] at the upper left of the screen, and then select [PERFORMANCE].
2. Has rekordbox dj been activated?
Enter the rekordbox dj license key included with this unit on the [Preferences] > [License] screen of rekordbox. For details on the activation, see the rekordbox software’s manual.
rekordbox Operating Instructions can be obtained from the rekordbox website.
http://rekordbox.com

If audio is not output or you cannot control rekordbox when using Windows, please see here to solve the problems.

[MASTER LEVEL] knob on the controller doesn't control the volume of the master output from the computer.
It controls the volume level of the master output, such as from speakers, from the controller.