Yamaha DTXpress/DTXplorer/DTXtreme

I remember some time back a discussion about the use of the 9/10 input to be
able to trigger 2 seperate sounds. I added a PCY80s and would like to use
the 9/10 inout to set up 2 seperate cymbal sounds on the original PCY60's. 

When I plugged in the two cymbals on a stereo Y cable I am still getting the
same sound out of both and it is only registering input 9. 

Any suggestions?

Scott