The In-Page Analytics plugin was developed to make it easier for you to view data pertaining to your site while you're on it.
For privacy and security reasons, it is important that access to this information be restricted. The rights you have been given in the Access Rights interface may limit the use of the plugin if a given site is not part of the scope you're authorized to view, or if you're only authorized to view part of it.
What's more, even if a site is part of your scope, you must have at least a "Read Data" level of access as it appears in the group creation interface.