Excellent advice Bill! I rarely use cruise and forget to mention that.
Gerard, the cruise can fail to operate because of a switch out of adjustment on the brake pedals. Sometimes the problem is the fender switch being dirty too. If the switches are fine, the problem could easily be a bad magnet exactly as Bill said. Lot's of magnets have gone bad or been bad from the factory. You wouldn't expect something so simple to fail, but it does.