One other thing to be aware of: I have the Garmin Speed/ Cadence sensor. There's a little white button (actually it's a light) on the outside of the unit. When I replaced my battery, I had to press the button so that my GPS unit would pick it up. You probably did this when you first set up your gear. I guess it has to be done every time there's a battery change. Just in case you may not have thought of it.