Using a Modal View from a TabBar View

I always get the following error: Error from Debugger: Previous Frame identical to this frame (gdb could not unwind past this frame)

I have an App using a TabBar. From one of the TabViews I need to display a View modally. I try:

if(self.gmailController == nil) {

	self.gmailController =
		[[GMailViewController alloc] initWithNibName:@"GMailView" bundle:nil];
}

[[self.navigationController] 
		presentModalViewController:gmailController animated:YES];

////////

And I have tried:

 [self.parentViewController 
 		presentModalViewController:gmailController animated:YES];

 	and 

 [self.tabBarController presentModalViewController:gmailController animated:YES];

 	and 

 [self presentModalViewController:gmailController animated:YES];

 Thanks for reading! Any comments welcome.

 Mark