Paid Membership Pro Wordpress plugin problem

Hi guys just setting up a membership site on wordpress and having an issue with the Paid Membership Pro plugin.

I have set it all up, membership levels, all the pages, paypal express gateway with my API creds etc but when i go to test and checkout with paypal it just opens a blank page.

Anyone had similar problems or know the solution?

Cheers

Maybe another plugin causing a conflict. Which others do you have?

W3 cache and thats it at the mo ill try disabling it.

Edit. Nope still nada!