Finally had my new boat delivered today. A 2002 Mobius that came from a far away state. Hooked it up to test it out, and it trailers beautifully. However, I cannot get it to back up. Feels like the brakes are catching. I mean it will not move an inch. Crazy thing is, as soon as I unhook it from my truck, it rolls around perfectly on the street. Is there a safety switch on this thing I don't know about? I have a single axle Boatmate Trailer. This is my fourth boat, and have never had anything like this at all. Any help would be appreciated.