How to add script to template using <?php include(""); ?>

[mmotp]

Thanks for reading.

I have a php slide show script I'd like to include on my vbulletin.
I tried go to the template and add this line to "header" and "headerinclude" block, but it doesn't show up.

<?php include("my script file.php"); ?>

I have tested this line in a blank php file, so the url path of the php file isn't the problem.

Where would I add the line to? Thank you.

Ren T.