$_SERVER['DOCUMENT_ROOT'] does not work in the php script running through cron

[goodmanmorx]

I use $_SERVER['DOCUMENT_ROOT']."/lib/sft_required.php"; to include the 'sft_required' file in a PHP script. When I run this file using browser, it works fine but when I run this as a cron job job, it does not work. It seems that the file is not included when we run the script through cron.