Reply to traktor pro 2 main volume very quiet!

I'm using traktor pro 2 with my numark mixdeck. Whenever I use deck B in traktor pro it is very quiet and the main volume on the top is high on the top bar and low on the bottom bar and so is only playing loud through the right speakers. All other decks are working fine. Please help! I have a gig coming up soon and can't find anything addressing this.