You should set proper permission to your server directories: Visit: http://bd1.php.net/chmod
<?php
// Read and write for owner, nothing for everybody else
chmod($first_sub ."/". $files, 0600);
// Read and write for owner, read for everybody else
chmod($first_sub ."/". $files, 0644);
// Everything for owner, read and execute for others
chmod($first_sub ."/". $files, 0755);
// Everything for owner, read and execute for owner's group
chmod($first_sub ."/". $files, 0750);
?>
just before unlink
you can call this function.