Hi info,
The addtosite.php would normally refer to the Connections/PowerCMSConnection.php file for the correct database connection details, but you don't seem to have 'PowerCMSConnection.php' in your cms/Connections folder, but have 'localhost.php' instead.
If that contains the connection details for the PowerCMS database, you would be required to update all the references to it in your pages, not a good idea.
Easier to ensure you have the correct details in a 'PowerCMSConnection.php' file in your cms/Connections directory.
Have you moved any other pages from their original (relative) location?