Shoutbox

you need to put the full URL to the index file, http://www.domain.com/folder/index.php
Or, the script might still be causing errors and be giving more than just the expected result.

When a URL is typed into the box, the script sends your email address as post data to the URL. If the URL is a valid YASS URL, the output of the file should be your MSN id number, as a check.
If the output of the page is anything but, it will give you that error message as you see it.