User Overview Addon Error

First off, thanks for an excellent plugin!

I just purchased the User Overview addon. After installing it and adding my license number, I get the following error:

Notice: Undefined index: addon_user_overview_enable_dashboard in my-wp-install-directory/wp-content/plugins/wp-slimstat-user-overview/index.php on line 56

Any advise on this would be much appreciated!

https://www.ads-software.com/plugins/wp-slimstat/