Error on checkout confirmation page

[nidhitiwari]

Hello Friends, I am getting a problem when i select payment method and go to the next page which is checkout confirmation and click on "confirm button" my page redirect to previous page from where i have already selected the payment method and I have to do this process again and again and then after i reached to "checkout sucess" page.But if i refresh checkout confirmation page then directly I reached to success page.I am not getting what mistake i have done please reply me soon.Thanks in advance