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

Hello All
I'm Larry and I have an MP7. when I go to Event edit and change the 
Program, MSB LSB that particular track will be erased or muted, in 
any case I cannot play the pads after I attempt to change the patch. 
I set the channel to ext. When I'm in int or both the events screen 
reads "no events in track". what's happening here or what am I doing 
wrong?...Thanks