[pwrdbym]

I have a 07 E92 328. The left side tail light on the car isn't functioning. All of the other lights (brake, signal) work in the same cluster. I have switched out numerous bulbs to no avail. I also cleaned all of the contacts and grounds with no luck. The fuses are also good (the rest of the tails work). I'm guessing something is bad in the circuit. I'm thinking of replacing that plastic bulb cluster (just the plastic piece that the bulbs plug into) on that side since it isn't that expensive, but I don't like throwing new parts at a problem if I don't know the cause. Any ideas?