Found the bug. Only took a total of 5 seconds for me to spot it.
Code:
<form action="{$URL_submit}" method="post" name="thisform" id="thisform" enctype="multipart/form-data" onSubmit="return checkForm()>
Is missing a comma right before the end. Please change it to:
Code:
<form action="{$URL_submit}" method="post" name="thisform" id="thisform" enctype="multipart/form-data" onSubmit="return checkForm()">
I'm also experiencing a problem with the "Edit Trackback or Summary" link not working. It should be ajax-revealing additional field(s) when you click on it. This might just be an issue with the latest SVN version of the template though. I will update the download in the next 15 minutes if you want to re-download the package for the comma fix. I won't be changing version numbers because of how minor the fix was.