Yamaha DTXpress/DTXplorer/DTXtreme

hey ive been drummin for 6 years now and just finally got my first
electric kit a yamaha dtxpress III special .. yah its a great kit
except when i play 2 many beats at any given time it will cut out the
sound such as i hit the cymbal it doesnt sound all the way threw and
sumtimes with the bass i hit it n it makes no sound when i play with
everything else ... its kind of hard 2 explain but when i use my toms
n cymbals n bass at the same time the sound of the cymbals gets cut
short and sometimes it misses a beat .. i was wonderin if ne1 new if
it was a problem with the module itself or something else .. i can say
ther is a mod on it for a 4rth cymbal but i currently dont have a 4th
cymbal hooked up 2 it .. thanks for the help in advance