Third Brake Light Problem

I had to use a file to clean the power buttons that make connection when the tail gate is closed, the sand paper did not do it! After it is cleaned up close the tail gate and have someone hold the brake down and connect the new LED light to the wires both ways to find the correct + & - to connect up the LED. I was by myself and used a mirror, volt meter and the new LED to be sure it was right before I finished the wiring.
 
Try cleaning up the four contact pads that make the electrical connection when the tail gate is closed. Two will be on the door and two on the Jeep tub. There may be some corrosion or something else making the connection week. Also make sure they are making solid contact. One other thing is that the wire colors coming from my 2005 wrangler are backwards from conventional wiring colors. The black (with color accent stripe) wire from the Jeep connected to the white wire on my light and the white wire (with color accent stripe) from my Jeep connected to the black wire on the light. Hope one of these two ideas helps.

Thank you for the advice. I placed a carpet kit in my 99 TJ and it moved and covered one of the tub connectors. I cut the carpet out an inch, cleaned up all four connectors and rear brake light works.