Getting 0 in beacon list in estimote beacon

here the code…in onBeaconsDiscovered the 2nd parameter list size is 0.

manager.setRangingListener(new BeaconManager.BeaconRangingListener()
{
@Override
public void onBeaconsDiscovered(BeaconRegion beaconRegion, List list)
{
if (!list.isEmpty())
{
Beacon nearestBeacon = list.get(0);
List places = placesNearBeacon(nearestBeacon);
Log.d(“Airport”, "Nearest places: " + places);
}
else
{
Toast.makeText(LoginActivity.this, “no beacon found”, Toast.LENGTH_SHORT).show();
}
}
});