Refitting E46 M3 rearview mirror

[Hian]

Hi,
Since having the windscreen replaced the autosensing wipers haven't worked properly so I thought I'd check all connections etc. Anyway, pulled off the mirror & now can't get it back on. I've taken off the whole unit leaving a hexagonal type nut on the windscreen which the mirror is meant to clip onto, howvever I can't seem to get it to refit - anyone any ideas? or is it a trip to the dealers?
cheers
Ian

[530dTPhil]

The mirror stem is supposed to be placed over the hexagonal boss at an angle of about 45 degrees and then rotated to the correct position, locking it into place.