Did you install the drivers?
When I start the program everything works fine on the mac, but on the controller (DDJ-RB) nothing is working, "hot cue" light, but no respons. I have used this program before and everything, but the mac crashed so I had to re download it again. but then this happened. It says that it connected, so it shouldn't be any problems.
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Did you install the drivers?
did it, but no respons
A couple other things to check / try...
1) Use a different USB cable and/or USB port on your computer.
2) Open the Audio MIDI Setup application and see if the DDJ-RB shows in the MIDI Studio window. Select the device, then click Remove Device from the top menu, then click Rescan MIDI and see if it appears. It should be a bright colour (as opposed to a faded grey).
3) Open the DDJ-RB Driver Version Display Utility and see if it shows the unit as connected, and take a screenshot so I can see which firmware / driver it reports:

i don't find "Audio MIDI Setup" application
It's under Applications > Utilities