Include php page

[Silver89]

I'm trying to include a php file with the following code as documented on the vBulletin pages, my plugin is setup as:

PHP Code:

ob_start();
  include('/header.php');
  $globalHeader = ob_get_contents();
ob_end_clean(); 


I then write - $globalHeader - in the header file where I want this include to appear? I have it setup with the host location of global_start but at the moment it just shows $globalHeader on screen and I'm not sure what's wrong?

Many Thanks