EDIT: I don't know what drugs I was on when I wrote this. Fixed the grammar
If you try to unlock the car too often, they don't come on. You do it once, lock the car, and try again, and they won't come on. Same with the interior lights. And if you lock your car too many times, the interior lights like to come on too upon locking for some reason... Weird. I had a friend who was way too eager to check out his new angel eyes on his 335 and he didn't realize that the car automatically does that.
If that's not it... there should be a setting in your iDrive or your OBC menu. Something to do with the daytime running lights. You might have inadvertently switched it off. Otherwise, there might be a power problem (bad battery, etc).
This thread might have further answers:
http://www.1addicts.com/forums/showthread.php?t=577488