Obviously not the problem here, but I had a ton of trouble pairing my 335i because the manual said to have the garage door opener about 12-16 inches away from the rear view mirror, which did not work. Thanks to a lot of forum browsing, I found out I had to literally put the transmitter right up against the rear view mirror. So when I programmed the Z4, I did exactly that and it worked the first time.
E89 Z4 sDrive35i 7DCT "Zayna", Alpine White/Coral Red
E92 335i 6MT "Calixta", Space Grey/Coral Red [Retired]