On my 6 pin to 7 pin adapter, the trailer brake and the 12 volt supply line pins can be reversed. Didn't know about this until I hooked up a buddies trailer and had full brakes all the time. The two pins swapped real eazy and was in the instructions for the adapter and was on my way. If you are not supplying 12v battery power back this could be your problem as it wouldn't apply the power to the brakes as mine did. Sorry, right now I can't tell you wich pins but will try to find it.

Hope this helps.