title: UIAlertView clickedButtonAtIndex is not called
body: <p>this is how I create the alert:</p>
  
  <pre><code>UIAlertView* dialog = [[UIAlertView alloc] init];
  
  dialog.delegate = self;
  
  //some options
  
  aField = [[UITextField alloc]initWithFrame:CGRectMake(20.0,45.0,245.0,25.0)];
  [aField setBackgroundColor:[UIColor whiteColor]];
  [dialog addSubview:appkeyField];
  
  [dialog show];
  [aField release];
  </code></pre>
  
  <p>However </p>
  
  <pre><code>- (void)alertView:(UIAlertView *)alertView 
                    clickedButtonAtIndex:(NSInteger)buttonIndex{
      NSLog(@"test here");
  }
  </code></pre>
  
  <p>does nothing. There is nothing in the log! What could be wrong?</p>