W164 Smart Key won't lock / unlock - resync ?

[speedcheese]

2010 W164 ML350 which now won't unlock or lock using the Smart Key, other than over IR when pointed directly at the door handle. If out of line-of-sight etc using RF, nothing happens.

I had a W163 before this one and there was a sequence to resync the key with the car - is there an equivalent for the W164 ? Or any suggestions what else may be wrong ?

I should add that this happens with both the keys I have, one of which has a fresh battery, so it is definitely not a battery issue.

 

[nictry]

Have had same issue on my 2010 ML for about 8 months, mine is more random works sometimes not others (even when pointing at ir in handle) both batteries changed and been in to MB around 6-7 times, they actually agreed to change rear SAM under warranty yesterday although they did eventually admit they had seen this same problem before and they never got to the bottom of it :fail