trailer Right light

I have been using my boat for about a month now.. but Today pulling home i was told i did not have right side lights at all.. I have an flat connecter pluged into round connecter.. that connector is what i plug into the back of my 2002 chevy trailblazer. The round connector has 3 indicator lights on it.. one R (rightt) and one L left the left light comes on .. on the connector.. The R light does not come on and the Right side trailer lights do not work eihter. I have tried Multiple 2 differnt roudn connectors they both show right side is gone. Sure seems to me my issue is with the trail blazer.. All lights on the trail blazer work fine .. all lights on left side of boat trailer work fine.. Any ideas..