Is it straightforward to convert a working Drupal 7 site to a Drupal 7 multisite configuration? I need to convert a site that is working with everything in the typical sites/all/themes,sites/all/modules,sites/default/settings.php,sites/default/files configuration into a sites/sub.example.com... configuration. I have tried moving the themes,modules folders into sites/sub.example.com/ but the theme and modules are not being found. The content etc is there but the theme and modules aren't.