Manage Registrations page is blank

When trying to access the manage registrations page I am taken to a blank page. Our site is behind a firewall so you won’t be able to access it, but the link is below.

https://10.xxx.xxx.xx/wordpress/wp-admin/admin.php?page=bookaroom_event_management&action=manage_registrations&eventID=186

I turned on error checking and received the following error if that helps any.

Fatal error: Can’t use function return value in write context in /usr/share/wordpress/wp-content/plugins/book-a-room/templates/events/showRegistrations.php on line 86