Upload Quotas Causing Dashboard Access Problems

Hi guys,

I am in the process of configuring ProSites for multi-sites (and allowing users to create their own subdomain sites). I am trying to get the Upload Quota Module to work, but somehow, when activated, it blocks all access to the dashboard on my primary domain site. The page error reads:

Fatal error: Call to undefined function is_user_logged_in() in /home/ss_main/simonsays.world/wp-content/plugins/pro-sites/pro-sites.php on line 1821

Hope there's an easy fix. Have tried deleting the plugin and re-installing, but that didn't work.

Thanks in advance!

Simon