DJM 900 Nexus Reverb effect problem.

Hey. I have about 2 years old DJM900 and now past 2 weeks i have had problem with reverb effect. When i put reverb on and use X-PAD all the way to right after 1-2 secods it starts cutting that reverb sound? Its like somebdy cuts that with corssfader its like that. If i just do swipe and dont let it on then it doesnt do that. Sry my bad english hope somebody understand