title: iBeacon: didRangeBeacons is not getting called when running app
body: <p>I prepared all the necessary stuff to setup a beacon region:</p>
  
  <pre><code>// Create a NSUUID with the same UUID as the broadcasting beacon
  NSUUID *uuid = [[NSUUID alloc] initWithUUIDString:@"E2C56DB5-DFFB-48D2-B060-D0F5A71096E0"];
  //raspberry pi:E2C56DB5-DFFB-48D2-B060-D0F5A71096E0
  //estimote:B9407F30-F5F8-466E-AFF9-25556B57FE6D
  
  // Setup a new region with that UUID and same identifier as the broadcasting beacon
  self.myBeaconRegion = [[CLBeaconRegion alloc] initWithProximityUUID:uuid
                                                                  identifier:@"monaLisaBeacon"];
  
  // Tell location manager to start monitoring for the beacon region
  [self.locationManager startMonitoringForRegion:self.myBeaconRegion];
  </code></pre>
  
  <p>However, didRangeBeacons is not always invoked. It invokes only once but then stops getting invoked. </p>