Emu XL-7 & MP-7 User's Group

I am trying to use the Mp7 as a sound module and use the pads with my 
mpc. I have them connected right through midi. The problem is when I 
lay a track down on my mpc say track 3 I choose a Percussion from the 
mp-7 cool it works fine. The when I go to track 4 and choose a bass. 
It turns track 3 into a Bass. crazy! might be something u guys can 
figure out simple.