'02 PASSAT Trunk lock

My '02 Passat trunk will go down but won't lock. The panel doesn't show any open trunk and the alarm arms correctly. Is this just a broken trunk lock?
I tried to lock it in having the trunk up and it worked. It just doesn't seem to engage and lock when the lid is pushed down.
If the lock need to be relaced, does anyone knows how much it costs and is it possible to be done by myself? The dealer might kill me on that..

I got that trunk lock problem fixed. Two local VW dealers offered different prices,$37.00 and $27.00. You might be asked for a Micro-Switch as well. In my case i used the one from my broken lock. The replacement took me some 35 minutes to do it. It was easy beside the trick to take that Micro Switch from the old one to the new lock.
If anybody is inerested, write me. I'll provide more details.