Trailer wire connection problem

On my camper the right rear stop light does not work. The right turn signal does, but not the right stop light. I traced it back to my '04 trailblazer where the problem is. At the trailer wire connection the right side stop/turn signal, only the turn signal work, not the stop light. The left side connection the stop/turn signal work perfect. All stop light fuses are ok. Any help would be appreciated

Thanks,

MPO85

Trace back the wiring in the harness and look for a bad/corroded connection.