I have a Kama meter on one of my cases and it works pretty good with 3 fans on it currently. Chances are you're blowing out the fan controller with too much power draw from your fans. I haven't seen any specs on what the limits are for each fan or the total wattage that can be drawn though. Maybe if somebody could print this spec somewhere less people would end up burning it up.
On a side note, 7 fans? That seems a bit excessive, can you even hear yourself think around it?
found the spec, it only lists per channel, not total. I'm assuming the total allowable draw is probably less than 4A though.
Maximum current per Channel:
1 Ampere (= max. 12W consumption)