Include PHP from global_start plugin won't work

[fumbler]

having a hard time with this and have searched threads and not able to get this to work.

Hook Location : global_start has this plugin:

PHP Code:

ob_start();
//global $main_xb_nav;
include('getenv('DOCUMENT_ROOT').'/includes/filename.php');
$outputme = ob_get_contents();
ob_end_clean(); 


template:

PHP Code:

$outputme 


Is there something that needs to be turned on in order for this to work? I have even tried setting it as a global var as suggested in one of the threads to no avail.

any suggestions?