Confirmation page not working

Assuming you have the redirect option enabled (in addition to filling in the URL for the redirect page there is a radio button to enable it), when it doesn’t work 99% of the time the problem is a Javascript error on the page which prevents the redirect from firing. You can see if this is your issue by simply loading the page suing something like Chrome’s developer tools and then examining the status. Javascript errors are usually pretty obvious in the console window and if you have any, the redirect will never fire and the plugin likely won’t work properly.