I have a convertible and have had some problems with the motor, but have sorted with the help of my friendly next door engineer!
On the motor there is a micro switch which needs to be set to on, have you tried that? The switch is switched on by using what looks like an allen key, which should be in the tool kit attached to the underside of the boot lid. If you open the boot lid, right infront of you is a small hole (about 8mm in size) the allen key fits in the hole, turning the key will switch the switch on or off, it only takes a slight movement, not sure if it is left or right, just try it both ways. Sometimes even though mine was switched on, I had to move the thing back and forward a couple of times to get it to work.