problem with relative header

I pulled some code off of the PHP site to use relative header info. I made the correction and removed the additional "/" and I've got in running fine on my development OSX machine but I've had problems on two different ISPs. Here's the code I've used; header("Location: http://" . $HTTP_SERVER_VARS['HTTP_HOST'] . dirname($HTTP_SERVER_VARS['PHP_SELF']) . "/webmgr_prop.php?action=1"); In IE I get connect errors. Once I put in a absolute paths it works. I'm working on a development server for one client who wants to move the pages to an "ultra top secret" server that I won't have access to so I would like to make it easy for him when he moves them instead of telling him what to edit. Unfortunately I only get a simple "connection error" message instead of the address that is failing so I can't see what part of the URL is not working. Any ideas? Tom