I can't control rekordbox.

Your mixer might not be not properly connected, or rekordbox or your operating system might not be able to recognize the unit as a controller.

■ Operating system
Mac users, follow the procedures in the guide [here].

Windows users, follow the steps in Case 5 in the section of this guide [here].

■ Others
You might solve the issue by doing the following:
- Disconnect any USB hubs and connect the unit directly to your PC/Mac.
- Disconnect any other USB devices.
- Quit all other applications.
- Connect the unit to a different USB port.