1995 STS brake Light Problem
 

The probem I have is when the headlights are on and you press the brake's the the left and right tail lights go out, the left and right center one's do work the 3rd brake light also works. I have replaced all of the bulbs and light sockets, but it seems not to have helped. When the headlights are off all of the brake lights all work? Has anyone seen this problem and can help me.