mirror install cant find wp-settings.php

so i copied my wordpress install to a subdomain to act as a test environment. i copied all the files, mirrored the database, edited wp-config.php and used the php script from the codes to adjust all the database entries. however when i go to the site i get the following error:

Fatal error: require() [function.require]: Failed opening required ‘<root>/dev/wp-includes/revision.php’ (include_path=’.:/usr/local/php5/lib/php’) in <root>/dev/wp-settings.php on line 120

i checked and the file is at that place so i dont understand why it cant find it. anyone got any ideas? google doesnt seem to find anything usefull about this