I experienced something really wierd I drove to work and got out of my car and went to lock my door with the remote and no matter where I stood it didn't do anything; so after 5 minutes I locked them manually which of course worked. When I went to leave I hit the unlock button and it worked fine, got in started it up and drove off no problems.

When I got home and pulled into my drive way I got out and clicked the remote to lock my door and it Worked?!?! I did this 5 or six times and it worked every time?!?!. I just left to go to the store a bit ago and when I got to the store the same damn thing happened I couldnt use the remote to lock my car?!?! Yet when I got home (out of the sun) is my only guess the remote worked fine again anyone ever hear or see this before..???

I am at a loss as to why this is happening ???

Battery in the remote may be dying....

Contacts may be loose/dirty. Have you ever dropped the key on cement or another hard surface?

All I can say is beware and always carry a second key just in case you can't start your car. A few months ago I got my key wet, it worked fine for at least 3 new starts, then miles away from home it unlocked the car but wouldn't start it. MB came an hour later and the guy could do nothing, I had to bribe the him to take me home and back with my second key as they are not supposed to let anyone in their car. Now I have to have the key reprogrammed. Haven't been dirving that car for a while. And actually before I got it wet I was having the same problem as you. Watch out!!!

My car was doing that EXACT same thing! I changed the battery and it still did it. I found that if I pulled the batteries out and re-seated them the car would lock.....and it always unlocked fine. Eventually I just switched keys with my wife 'cause hers seemed to work fine.

In the end I ended up mentioning to the dealer the last time I dropped it off for service. They ordered two new keys for me and swapped 'em both out. I dunno if they had heard something about this in other cars or were just being nice to me after the whole "replace the entire fuel system" incident I posted awhile back.