If it's working with other trailers, I'm wondering if the brake controller is not compatible with the trailer brakes.
Did you ever figure out why it wouldn't work?I got my Rebel with the integrated trailer brake, and yesterday had a boat trailer hooked up that has a brake. The brake wouldn't engage and when I tried to adjust the setting I got a message indicating "trailer brake not connected" but it was. I know it isn't the trailer, on my previous Ram I also had the integrated brake and it worked fine. Any thoughts?