I only requested two new keys.
I called them just now to confirm.
They no longer put the red dot on them.
But when you order from MB direct, they are properly keyed/stamped to work the factory alarm.
Start with a good key (mine were pretty worn when I compared side-by-side). If you order from the dealer, and you still have problems with your "factory" alarm, then it probably is in the locking mechanism. In my case the new keys solved the problem ..... for now.