Error on site when Infinite SEO is installed

Here is the error the appears at the top of my site or admin page whenever INFINITE SEO is installed.

Warning: Creating default object from empty value in /homepages/22/d444077125/htdocs/ironspringsdesign/wp-content/plugins/wpmu-dev-seo/wds-files/wds-core/wds-core-wpabstraction.php on line 12

How can I fix this? Thanks, Tim Lewis
tim@ironspringsdesign.com