If i set my device id on setTestDevice(), i get those messages in LogCat and nothing appears:
03-11 23:37:33.402: I/Ads(24309): Use AdRequest.Builder.addTestDevice("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX") to get test ads on this device.
03-11 23:37:33.412: I/Ads(24309): Starting ad request.
03-11 23:37:34.193: I/Ads(24309): No fill from ad server.
03-11 23:37:34.193: W/Ads(24309): Failed to load ad: 3