403 loadig a php file

hi, im using wp-filebase and it loads css via a php file (do some cache comprovations), but it always return 404 (403 if i disable permalinks), but is not only that file if i make an php file in any other directory and get the same, the monday all was working ok, but now it fails.
i also tried changig permisions to 644,755,777 buit no one work

if i link directly to the css file all get fine so, any help trobuleshoting this?