Just my 0.02$ worth, but I see you define your directory $file_folder using a relative path.

So, when you launch this script in a directory where there is no foo/foo2 subdir, you'll get this error. And certainly when you run if from apache, you will look for the directory where you start your httpd daemons, which might be / or /usr/local/apache depending on your config.
---------------------------
Dr. Mark Ceulemans
Senior Consultant
IT Masters, Belgium