In Garageband, why won't the Roland HD3 V-Drums hi-hat trigger any midi at all? (It works when it's used as audio)

Question

My drummer bought the Roland HD3 V-Drums recently, and I bought a Mac Mini (to record on Garageband).
When we record as audio from the V-Drums (using an audio interface) everything seems to work fine - but (of course) we can't change the sounds etc as it isn't midi (and we want to use midi).
When we record as midi from the V-Drums (using a midi to USB cable) there are two major problems. Firstly, the hi-hat doesn't pick up at all - despite the fact it works when it's used as audio. When the hi-hat is hit, it doesn’t trigger any midi at all. The second is that the drums occasionally trigger a double hit. This issue I can get over (though it is annoying and it shouldn't happen) as I can manually delete any extra hits.
I wouldn't expect two expensive pieces of kit (Apple Mac and Roland V Drums) not to work perfectly on something so simple. Please can you advise me of how to resolve this?
(For info, I've emailed Roland the same issue too.)
Thanks.

Answer 1

While connected to GarageBand hold down Variation and 7 on the HD-3 to reassign MIDI codes.  Garageband does not recognize the HH "edge" codes so I changed both of these (HH OPEN EDGE and HH CLOSE EDGE) to match the value for the "bow".  With the HH pedal down, hit the center of the HH pad, the screen should say HH CLOSE BOW.  Remember the code, then hit the edge of the HH pad.  The screen should say HH CLOSE EDGE.  Use the Up arrow button to set the value for the HH CLOSE BOW.  Repeat the same steps with the HH pedal up so HH OPEN EDGE uses the same code as HH OPEN BOW.  To reset any pad to factory value hold down up and down button at same time.   Hope this helps!