Have a similar problem on our 2001 estate. O/s rear tail light not working. Bulb replaced, but continuity of one removed is fine. Brake light is OK and as it's in same bulb, earth must be fine. Haven't checked fuses, but as other lights all work, can't see fuse is issue. Hope it's not wiring loom.
Did you check fuses/earth?
Did you fix yours?
sean
January 2009