title: NavigationController becomes nil after popToViewController
body: <p>My navigationcontroller becomes nil after my "[self.navigationController popToViewController: [self.navigationController.viewControllers objectAtIndex:0] animated:YES];"</p>
  
  <p>this is my scene:
  InsertViewController - > <pre><code>[self.navigationController pushViewController:choiceViewController animated:YES];</pre></code></p>
  
  <p>ChoiceViewController -> <pre><code> [self.navigationController pushViewController:choiceDetailViewController animated:YES];</pre></code></p>
  
  <p>ChoiceDetailViewController -> 
  <pre><code>
  InsertViewController *insertViewController =  [self.navigationController.viewControllers objectAtIndex:0] ;
  UINavigationController *secondaryNavigationCtrl = [[UINavigationController alloc] initWithRootViewController:insertViewController];
  secondaryNavigationCtrl.navigationBar.barStyle = UIBarStyleBlackOpaque;
  [self presentModalViewController:secondaryNavigationCtrl animated:YES];
  [secondaryNavigationCtrl release];
  [</pre></code></p>
  
  <p>When "ok" button pressed( self.navigationItem.leftBarButtonItem) in InsertView that just poped up, then it goes back to ChoiceDetailViewController and i do a 
  [code][self.navigationController dismissModalViewControllerAnimated:YES]; [/code]</p>
  
  <p>After that i do a 
  <pre><code>
  [self.navigationController popToViewController: [self.navigationController.viewControllers objectAtIndex:0] animated:YES];
  </pre></code>
  Which go back tot the InsertViewController, and when i do the cycle again i see my navigationcontroller is nil...</p>
  
  <p>Any idea what I am doing wrong?</p>
  
  <p>Thanks in advance.</p>