dismissModalViewControllerAnimated doesn"t return

If I push a view onto the Navcontroller it works great and I can return from it either with code or using the Nav Controller back button.

Then I change it to present the view modally. The preset works but I cant get it to return and dismiss the modal view.

This works... main view

Tools *screen = [[Tools alloc] initWithNibName:@"Tools" bundle:[NSBundle mainBundle]];



     [mainNavController pushViewController:screen animated:YES];



    [screen release];

One the modal view:

- (IBAction)btnCancel:(id)sender {





  [self.navigationController popToViewController:[self.navigationController.viewControllers  objectAtIndex:0] animated:YES];





}

But then I change it to modal like this on the modal view it does not go back to the main view.

Tools *screen = [[Tools alloc] initWithNibName:@"Tools" bundle:[NSBundle mainBundle]];



 [mainNavController presentModalViewController:screen animated:YES];



  [screen release];

On the modal view:

- (IBAction)btnCancel:(id)sender {





    [self.parentViewController dismissModalViewControllerAnimated:YES];





}

I have tried about everything I can think of, obviously I am missing something! Any ideas?

thanks for any help!!