Test light first to see if the bulb holder is actually getting power and go from there.
Make sure you check the actual bulb holder to see if it's not corroded, take it off the back of the light and lightly sand the connections inside the bulb holder. Take the bulb out and make sure the filements(sp?) are still intact, if not you need a bulb.
See if you can get ahold of another light and see if it lights up. If it does then you know you need a new light. Cause the board might be fubarred.
1994 318is-Sold July 13th 2010.. Sad Sad Day