I'm having a strange issued trying to change non-cgi path.

I get this error:

The config.inc.php file found in your /home/mydomain/ubbthreads/includes directory is not writeable. Please fix the permissions on this file and try again.

However, I checked the permissions via my FTP client and it checks out OK. And, the permissions check in CP says the includes directory and all files are OK.

What else could be the problem?