2001 c70, Offside Head lamp wiper not working.

[Cribly]

The offside head lamp wiper is not working on my Volvo c70 convertible.
I have taken the motor out and tested it and it seems to work just fine. The first time I had it out I took the motor unit apart but put the electric motor back in the motor housing the wrong way round, and when I put it back in the offside wiper was working consistently when I turned on the ignition. Now assuming the evening thing was in reveres I thought that Turing them on would turn the offside off, but this didn't happen. What happened Instead was that the nearside turned on and the offside carried on going. I than took out the motor housing turned the electric motor round the right way, tested and replaced, but the offside still didn't work. My only assumption is that there is no message going to the motor to tell them to turn on. Any help in figuring out why there is no message going to the offside head lamp motor would be great.
thanks Chris.