Blank white screen membership pro shortcode

Hi support,

I purchased membership pro after using the light version for a couple of days, and seeing it worked decided on getting the full version.
However, now, when I 'create page' in options>membership pages, the page is created but when I click on 'view page', or try to access it via the link on my site I get a blank white page. Also if I try to access a different level from the main page (admin panel), then too I get the same white page with this redirect: http://i-english.nl/wp-admin/admin-ajax.php?action=membershipuselevel&level_id=9&_wpnonce=5e5dc70b50

..instead of the i-english.nl/register page it should go to. I have now deleted everything, the pages, the plugins and all my other plugins to see where the problem is but to no avail.
I set WP-DEBUG to true and got something about 'plugin.php see line 580'.

Everything worked before but now I can not set up any subscription pages or registration pages.

Hopelfully someone can help..

Thanks!