When I move the crossfader to the side where a deck is playing, no sound is output. Why not?

The crossfader settings might not be set in the way you want the crossfader to work.

・Check the crossfader reverse setting.
Press the [SHIFT] button. If the [FX1/CUT1] button flashes, the operating direction of the crossfader is reversed. In this case, press the [FX1/CUT1] button while pressing the [SHIFT] button to turn off the crossfader reverse setting.

For details, see [Switching the modes of FX/CUT buttons] in the Instruction Manual.

You can read the Instruction Manual [here].