If there is no script installed in the root for your domain name but you still get this message it means that a previously installed script was not properly removed. In order to solve this issue you should follow these steps:
1. Log in cPanel and click on File Manager;
2. Navigate to .fantasticodata in your Home Directory;
3. Delete the file installed_in_root.php.
This will ensure there is no Fantastico information remaining from previous installations.
If you have problems with your Fantastico, ask your host for assistance.