I am assuming you have imported a standard midi file with GM program changes, correct?
take a few minutes to read starting on page 632 of the manual that deals with smf's since they work differently in Logic than in cubase or any other sequencer
if you are importing smf's with GM program changes, as a default behavior, Logic Pro will automatically create software instrument tracks for each MIDI track, and assign an appropriate GarageBand instrument to each, when you open a MIDI file. If you want to use external MIDI tracks for each MIDI track, press Option while opening the MIDI file.
if there is no GM equivalent, sometime Logic will open it into an external midi track. That has happened to my drum track more than once. Create and instrument track and load a drum set and drag the midi region to it.
now this is very important:
An import only loads MIDI region data (notes, controller, SysEx, pitchbend, specific meta events) into an opened project, with global data (such as tempo events, signatures, chords, track names, SMPTE start, and so on) being ignored. Important: If you want to load all information contained in a MIDI file, you must open not import it
Have Fun! and make sure you read up on this on page 632
Don
