getting a PHP script to run in VBB

k...

I have a script like this

<?php

echo "hello";

?>

and its in the postbit template. when Its run, nothing happens. I view the source for the page, and you see the <?php. I have the code in the right place, but it doesnt want to 'run'

how do I get vbb to recognize that I have a script here, and php should run it.

thanks