I haven't had problems in Wii Fit with my remotes or nunchuks not working but some other games seem to be an issue. I found this site that explains quite simply how the remotes detect motion.

http://www.scienceline.org/2006/12/18/m ... ntrollers/

Sort of explains why when it doesn't register a movement in EA Sports Active and I give it a shake it comes to life again.

I have no problems with the motion sensor when playing Wii games created by Nintendo. But games that other companies make for the Wii do not work nearly as flawlessly & seamlessly as Nintendo created games. I wonder if sensor technology has anything to do with it . . .