did it ever work? if not, then have it checked by BMW as it may be switched off. I had this on my lexus and i found that if i had the keys in my pocket and the button was pressed all my windows opened, i got fed up waking up in the morning and seeing all the windows of my car wide open. Also happened in a public car park.. i i had then turn this feature off. If it has worked before then it may be the batteries in your fob, or a faulty fob.