Yamaha DTXpress/DTXplorer/DTXtreme

I just received my DTXpress for a Christmas present. I often play the 
kit along with some of my favorite CDs, however, I'm only getting the 
music in one ear and the kit in the other ear. Is there a way to get 
the drums and music in both ears?

I'd apprectiate any help I can get.

Thanks

John