crashing on ios device while navigation using UIModalTransitionStylePartialCurl in xcode 4

i am using UIModalTransitionStylePartialCurl on the ios 4 device,in my test app i have 2 classes where a single button in each class, in first page onclick of the button it ill navigate to 2nd page (by curling the page up) but in the 2nd page when i click backbutton its crashing but not navigating back to my first page following is my code used for navigation

ViewController *MainWin = [[QIAViewController alloc] initWithNibName:NULL bundle:NULL]开发者_StackOverflow中文版;
    MainWin.modalTransitionStyle = UIModalTransitionStylePartialCurl;
    [self presentModalViewController:MainWin animated:YES];
    [MainWin release];

this is the crash log:

 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present a nested modal view controller while curled <QIAAdminPassCnf: 0x583e040>.'
*** Call stack at first throw:

If you read the documentation for UIModalTransitionStylePartialCurl, you will see that once you've used it you can't present any more modal views.

If you want to navigate back, I think you should do,

 [self dismissModalViewControllerAnimated:YES];

rather than creating a new view controller instance.

You may well have added the Action twice in Interface Builder. Go to the ViewController and to the Triggered Segues on the right and "x" do delete the extra one. LOL