My left brake light is out. I already changed the bulbs, and I also checked the fixtures to see if they were getting power. They are. Does anyone have any suggestions?

you said that you checked for voltage, where did you ground your lead? it could be possible that you have a bad ground at that socket (or side). do you have a multimeter (that you can check resistance) with (to see if you have a good ground)? g/l - sos