I bought a used Simmons SD5K that came with a KD8 kick pad and pdp double bass. The pad was visibly damaged and did not work, so I bought a new one from Musician's Friend, thinking that would fix it...this one delivered no sound when hit with a bass pedal, and only delivered a very weak sound when hit very hard with a drumstick. I know all the cables and inputs all work fine, because I tried switching them all around. I have tried putting the gain and pad sensitivity all the way up, which did not help. I exchanged it for another KD8 which has the same problem. I'm wondering if there is a compatibility problem between these two products, or if not, what the problem is?