Few things to check.
a) the click track takes up a voice, so if you already have 6 voices playing you won't hear the click.
b)the sequencer has limitations, i think its 8 slots if i remember rightly, so if in the bar 1 beat 1 you record information for 8 different pads if you try to record more they are just ignored until you free up some slots for that particular timeslot in the sequencer.