Bluetooth keyboard malfunction after win7 update

As in the object my bluetooth keyboard dosn't work after a win7 update on bootcamp.

After several tries it semms to pair again but the disappear

I tried to reinstall bootcamp driver but nothing is changed.

My magic mouse works correctly. Only the keyboard is missing.

Please, any ideas?

I dont' want a USB keyboard to use with a 2000 dollars Mac

😮