3.8 to 4.0 upgrade breaks file include Plugin

[EnvanoVB]

Under the plugin manager I am currently using the following:


ob_start();
$blockHBX = true;
include($_SERVER['DOCUMENT_ROOT'] . '/lib/header.inc.php');
$header = ob_get_contents();
vB_Template::preRegister('header',array('header' => $header));
ob_clean();
$miller_forumbanner = 'projectsforum';
$miller_noinc = true;
include($_SERVER['DOCUMENT_ROOT'] . '/lib/footer.inc.php');
$footer = ob_get_contents();
vB_Template::preRegister('footer',array('footer' => $footer));
ob_end_clean();


In my 'common template' header & footer area I am using the following:


$header
$footer


Yet this is not working. it just renders it as normal PHP. Can somebody help me to get this working?