mapping drum midi in garage band

Hey!,

Using a Roland Drum Kit, running Apogee Duet, Macbook Pro OSX 10.6.8.

Having troubles when using MIDI. The High hat is not working properly (when I press the pedal down nothing happens, the sound is sometimes splashy sometimes half splashy or not at all), The crash symbol is having issue and also the ride symbol wont splash.

I think its an issue with the signals between the Roland electronic unit and garage bands drum kits. I am wondering how can I map the midi? Programs to do it with? What notes do I use to map them?

Cheers,

Grant