Wiring SVC subwoofer in place of stock DVC sub?

I am running a 4 channel amp and have attempted to hook up my single voice coil sub to the system. Instead of there being a dedicated sub amplifier I am running it off the same amp that drives the speakers I am attempting to bridge my 8" Rockford P1 SVC sub but when I hook everything up and play it, I the sub seems to be cutting in and out. What gives? It's hooked up in a 4 ohm load, as the sub is a 4 impedence sub as well. A little help please? I am using the old sub wiring as the input to the amp and am running the current wiring that comes from the stock box setup to the sub.

 

Nevermind. I got it. My postive and ground was backwards and upon reversing channel polarities to the sub it started working stellar immediately.