OnLocationChanged() not being called on the device?

Question

Android

I have some trobule using Google Maps API on Android. In onLocationChanged() I create an overlay and add it to the MapView, which works fine on the emulator using Android 2.1, but when I try to debug on a device, nothing happens. What could be the problem?
The device is Sony Ericsson Xperia Arc with Android 2.3.
Thanks, Ivan.
There is an overridden onLocationChanged() method from the Google Maps API that fills the map when the position changes. In the emulator everything works fine, but on the device (XPeria Arc with Android 2.3) nothing seems to happen. Why is this happening?
Thanks in advance.