2005 chev avalanche: right brake light doesn't work even though all other functions work. That bulb works in all other sockets. Also both filaments of that particular dual filament bulb work in that socket and all others for the purposes of blinker and night lights, etc. All fuses checked. Junction box under right quarter rear panel opened and clean. The only thing it won't do is light up when brakes are depressed. Only on one side. Help?