Refer to default vbulletin variables in plugin code

[OscarJohansson]

Hi,

I haven't been able to find the answer to this through google or my forum searches.

I have a custom header on my forums which uses my custom plugin to like this to load it:
{vb:raw addTop}

The plugin looks like this:
ob_start();
$addTop = include_once('topHeader.php');
$addTop = ob_get_contents();

vB_Template::preRegister('header', array(
'addTop' => $addTop
));

ob_end_clean();

It includes my external php file. So far so good.

Then started adding custom vb variables in the header such as {vb:raw bbuserinfo.pmunread}
{vb:rawphrase control_panel}
{vb:raw bbuserinfo.username}
etc

Problem is that these variables don't seem to get rendered for some reason. The output is the actual string {vb:raw bbuserinfo.username} and not the username. What is the problem and how would I be able to sove it?

Thanks