Either missing or misplaced include line.
Look for the following code on your page:
<?php require_once("WA_Universal_Email/mail_PHP.php"); ?>
it should be near line 1.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.