Sounds like you are using midi that was created using another soft synth.
You could re map every thing but you might be better off just opening Piano Roll View and clicking on the header notes (to select every kick drum, every snare, exc) and drag the notes to their corresponding midi notes.
OR:
Just use the map that comes with session drummer.
Use the
Insert > Soft synths > Session drummer 3.When session drummer 3 open, load a kit. Create new midi in PRV or using a controller OR copy/paste the midi one by one from the previous midi track.
paul jenkins
why is it different? annoying!!!
Because they are made from different vendors Paul. nothing we can do about that man.

Its all part of the game we play called: DAW-nopoly.