FPC problems

I need the skill of a technical engineer, or sound designer. Can someone please tell me - I am presently in the Piano roll trying to create a drum beat using the Expansion kit Power, why does the two drums I need (low tom and floor tom, and kick) refuse to allow me to input sound. In fact only some of the drums will allow me to input a hi hat, but not kick and snare. It jumps past the drums I need and lands on the drums I do not want? Is my system corrupt because it has been like this foorever but now I am writing a new album I need this to be working and I can't figure it out.