Your file or a file used by the php file is the wrong permissions (777 or writable by everyone).  You need to change the file to 744 or 755 permissions (not writable by group and everyone). 

For security purposes, our serveris configured to run PHP in suphpexec mode.  This means that instead of all users on the server running PHP code as a nobody user and possibly effecting other users scripts, we run PHP as your admin userid.  This allows PHP code to have read, write, and execute priveleges to files you upload to your website. 

Some scripts and programs need this write ability and therefore tell you to to make folders and other items 777 or full permission for everyone.  This is very unsafe and therefore prevented to be allowed by the server.