2001 A4 alarm/locking problem (VAG-COM)

   I am having problems with my alarm/locking system.  I bought this car used in Dec. 07 with 56k miles and didn't have any problems until Feb.  At first, once in a while the horn would not beep when I locked the door.  This started happening more often, and now it is the norm. Whenever the horn does not beep if I lock it, the alarm will go off after 5-10 minutes.  I know it's not the internal sensor because I have lowered the sensitivity with VAG-COM.  A few weeks ago my CEL light came on and I mentioned the problem to the mechanic, but he said that he couldn't get the alarm to go off. (He left it locked for minutes-hours at a time).  Whenever I had my car looked at for any reason (oil change, after CEL was resolved), the horn would honk the next few times I locked the door, but the problem always came back.  I have resorted to locking the car by reaching over to the internal button from the passenger's side.  Does anyone have an ideas?
 
 
EDIT:
 
Basically what I want to know is: is it possible to use VAG-COM to make my car think that it doesn't have an alarm system?  I want it so that when I lock my doors with the keyless remote that the anti-theft is not activated.  Has this ever been done before?

(forgot to subscribe...)

when you don't close a door properly the horn won't sound if you try to lock it with the remote but the car will still lock. this includes the trunk door

I know that all the doors, trunk, and hood are "closed." I think that it might be a sensor thing.