Yamaha DTXpress/DTXplorer/DTXtreme

I've got a weird situation here. I'm trying to send a MIDI drum
sequence to my Yamaha DTXpress III to be played back. Trouble is, it
doesn't play. The DTXpress is receiving the data, and in fact will
play any MIDI sequence EXCEPT drums. I.e., if I just send a standard
MIDI file to it, all instruments except the drums will sound! It's
apparently ignoring anything coming in on channel 10. Is there some
particular setting in the DTX that would cause this? I've been able to
play MIDI drum tracks through it before, and as far as I know, I
haven't changed any settings.

In the utility menu, setting are as follows:

UT MIDI RECEIVE:
10PC=on
10=on
PC=on
SysEx=on

UT MIDI SETUP:
MIDI Mode=native
DevNo=ALL
Locl=on
Merge Output=off

Any help would be appreciated.