Can't hide Header and Footer on one page

Hi there,

We’d like to hide both the header and footer on out Order Received page. Please see attached link.
In the Page Attributes, we’ve set the parent to Checkout and the template to Blank – no header, no footer. In the Layout, we’ve set: no sidebar, no socket or footer, hide both title bar settings and under transparancey – hide header on this page. Despite all this, the page stil shows up with the header and footer that we use for all other pages.

The issue has arisen by the way because we have two websites but only one PayPal account and therefore only one auto-return thank you page so we need this page to be without any branding that would confuse people who purchase on either site.

Many thanks,

Robert