When I tried to connect to a SharePoint URL in dashboard designer options, it prompt a message saying "The URL is not available, does not reference a SharePoint site, or you do not have permission to connect"
When I checked the Event Log under Administrative Tools -> Event Viewer -> Windows Logs -> Application, message says that
"Cannot open database "WSS_Content_GuidOrGivenName" requested by the login. The login failed.
Login failed for user 'domain\username'."
The reason is that the the Service Account under which the PerformancePoint Service runs, does not have permissions for the SQL Server Content database of the SharePoint Web Application.
To fix this issue , add the domain user which uses to run PerformancePoint services as the database owner of the Content database of the web application (WSS_Content_GuidOrGivenName).
After that you will not get that message...