Brake light comes on on tow vehicle towing camper ???

After about 30 to 50 miles down the road towing camper, brake light comes on on our 2012 Dodge Durango . I suspect it is because the trailer brakes aren't being engaged well nuf by the brake controller. Is it possible for the Durango brake computer to pick up the extra load on the brakes and turn on the light ? If I play with the brake pedal and get the trailer brakes to engage, the light seems to stay off.
I definitely want to try another tow vehicle brake controller, what is the best performing brake controller now on the market? I hear about something called the Prodigy.