I bought a nice Big Tex trailer used off of craigslist, it's in great shape but the only issue i am having is with the breaks. I have a 05 GMC sierra 4x4, I bought a reese control box, plugged it into the factory pigtail (used the correct wire diagram to match the correct wires) plugged her all in and it gives me the signal that the controller is plugged in correctly but says that the trailer is not connects?? I'm not sure where to start to look. I've checked to see if there are any fuses for trailer brakes, only found one fuse under that dask and it just says brakes. So any insight from you guys would be great.