locationManager didFailWithError

from 1 week if my gps app fail to retrieve signal (eg: testing in my home) i don't receive any aler. i've setup my error notification in this way

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {      NSString *errorType = (error.code == kCLErrorDenied) ? 
@"Access Denied" : @"Errore sconosciuto"; 
UIAlertView *alert = [[UIAlertView alloc] 
                      initWithTitle:@"Errore recuperando la Location" 
                      message:errorType 
                      delegate:nil 
                      cancelButtonTitle:@"Okay" 
                      otherButtonTitles:nil]; 
[alert show]; 
[alert release]; 
} 

for what reason app do not retrieve data and do not show me the alert popup?