Land Rover Repair: 2002 Land Rover disco II door lock problem, tail light, temperature change

Question
I purchased a 2002 discovery II w/ about 61,000 miles on it a few weeks ago.  I love it so far but I noticed a week later the passenger side tail light went out.  I successfully changed the tail light the other day but for some reason now the passenger side door lock isn't properly working with the remote key anymore.  When the door is unlocked it will lock but if it is locked, and I going to get into the car, the lock will not open.  2 observations 1.) this happened right around the time I changed the passenger side tail light and 2.) There was a bit of a cold snap, temperature change right around that time.  I don't know if these things could have contributed to the problem but I thought I would include them.  Anyway- Do you have any idea what the problem might be? - before I take the car in to get fixed?
P.S. Anyone fixing their tail lights I suggest taking the problematic one to the store with you.  For some reason the 2 different stores I went to referenced the same bulb, and they were both wrong in the stores computers.

Answer
First of all, I personally do not think that there is any relation between the tail light bulb and the door lock operation. As far as the door lock goes, the most common problem is the internal failure of the door latch itself. The latch will have to be replaced.