2001 Chevy Suburban Brake Lights Not Working

I have checked fuses, bulbs, replaced brake light switch, but brake lights still not working. The LED brake light works fine, as well as hazards, turn signals, running lights, etc... The cruise is not working, but it is my understanding, that without recognizing the ground through the brake lights it would not work. I have a factory installed tow hitch and have checked the system thoroughly. I have power in and out of the fuse in the box under the hood, additionally I am getting power to the trailer lights plug when brake is applied, but nothing at the brake lights. There has to be something that I am missing. Please help. Any information you can give me would be greatly appreciated.