Reply to need help...

I just purchased a Pioneer DDJ SX and installed the driver and Serato DJ. I launch Serato DJ an turn on the DDJ and all is good as far as the software recognizing the controller. The problem is that only deck 4 will play and nothing else. When I load a track into deck 1 2 or 3 there is no sound. Only plays in deck 4. What am I doing wrong. I did try to reinstall Serato DJ, no luck. I'm on a PC.