wordpress and paypal page redirect

Hello,

I have set up a shopping cart in paypal, and everything is working nicely! i want to redirect the customer back to the website after they purchase an item, I have set this up in paypal by turning on auto return and i have also set it up when creating the add to cart button.

I have created a thank you page especially for the redirect, but the problem is that when the customer checkouts and pays, it redirects them to a page that cannot be found, it says This is somewhat embarrassing, isn’t it?

anyone know what i’m doing wrong????