Crosspost from hardware because I thought somebody would be more likely to help here

I'm using a Midiman USB Keystation 49 on my AMD-based OSx86 10.4.8 comp. It shows up in the Audio MIDI Setup interface but doesn't make any sound in Garageband, Logic Express, or the Audio MIDI Setup test mode. I downloaded the drivers from M-Audio (version 3.2.2 I think). The keyboard works great on my late-model iBook in 10.4.9.

I have exactly the same keyboard and an Athlon x2 based computer and works perfectly.

In fact drivers are not neccesary at all.

Just push some keys and see if you get activity in logic´s midi monitor (right part of the transport)

It says

No in
No out