Yamaha DTXpress/DTXplorer/DTXtreme

Alright, I'm a little bewildered again, but I'm sure you all will 
help me out!  When I'm playing a basic beat with just the HH, snare, 
and bass drum, my HH will sometimes skip the production of a sound, 
while the snare and bass drum can go on forever.  I've read about 
this on here before, but I don't know where now, and I know I have 
to mess with the spec rejection and not just the regular rejection 
right?  Once I'm there, whose spec rejection level should I mess 
with?  The snares or HH?  And if you messed with some settings 
between these two and they work right, let me know about it! :)  
This HH is ruining my life!  Thanks!