What year are your vehicles? I've never been able to program mine.Finally got my garage door openers programed on my W210s!!!!
I bought a new garage door opener several months ago and couldn't program the W210s for some reason. Didn't have any problems before or on my W203.
The solution was to erase the old codes by holding the outer two buttons down until the light starts flashing rapidly AND keeping them down for approximately another 20 seconds until the light goes OFF!
Happy camper again