I had the dealer install a OEM hitch when I bought my Hemi. My utility trailer has the 4 post connection so I bought an adaptor so I could plug it into the round connection on the hitch. The running lights on the trailer work but the brake and turn signals do not. Any Ideas what could be wrong? The trailer guy looked everything over but could not find a problem. Told me to take it back to the dealer. If it's an easy fix (like moving the luggage rack crossbar so the satilite radio works) I'd rather not make the trip out to the dealer. Thanks for any help!