PHP include

[Quotaless]

I need help installing:
<?php
include ("test.php");
?>
on my header template.

When I try it, it doesn't work. Is there something that I'm missing?

[BBR-APBT]

<a href="http://www.vbulletin.com/forum/showthread.php?t=173937" target="_blank">http://www.vbulletin.com/forum/showthread.php?t=173937</a>

[Dismounted]

<a href="http://www.vbulletin.com/docs/html/main/templates_externalfiles" target="_blank">Including External Files</a>