User assignable buttons problem

I have just installed windows 7 on my system and updated from Cubase 5 to Cubase 6.

I had CC121 working fine on Cubase 5 and Vista, but now I am unable to get the user assignable buttons to work. When I, for example assign ‘mixer’ to button number 1 it doesn’t respond at all.

I can reset to the defaults (they work, a bunch of zooms) but cannot change from that. I’ve installed the latest tools update.
Any help appreciated .