Tail light problem

[DrtyRat]

Alright here's the deal...I have a 93 240sx (coupe) and for some reason I cant get the tail ligths to work at night and/or when I turn my head lights on. Every other bulb works fine including the brake light filiment in the same bulb, but I can't get the lights to come on. I had one bad socket where the wire had rotted off but I already replace it. I know its not a fuse problem(like i said the rest of the lights work fine) or a socket problem b/c the brakelight filiment in the same socket works fine. Anyone got any ideas why only the night time lights(don't know the proper term) are the only ones that don't work?