Pontiac Repair: license plate lamp

Question
QUESTION: My license plate lamp is out.  I've changed the bulb with no luck.  I can't figure out what fuse it is on as everything else seems to be working?  Where do I go next?

ANSWER: model and year of this car? Do the parking lights work?



---------- FOLLOW-UP ----------

QUESTION: 2004 aztec.  all other lights work and the socket seems clean.

Answer
the license plate lamp on that truck is tied in with left parking light. if the left rear parking light works you have power and ground to the back of the truck. if you check it with a test light at the socket and you are missing the power or ground it's a good chance the wiring is broke in the pass though for the end gate being that the wire moves every time you open and close the drop gate. that is a good place to look.