Javascript help

[SpankMe]

I need to add a function to the newthread onsubmit, but I can't get it to work. It only executes the first function, no matter what one I put first.

I changed this:
<form action="newthread.php" method="post" name="vbform"<if condition="!is_browser('webtv')"> onsubmit="return vB_Editor['$editorid'].prepare_submit(this.subject.value, $vboptions[postminchars])"</if>>

into this:
<script type="text/javascript" src="clientscript/vbulletin_trader.js"></script>
<form action="newthread.php" method="post" name="vbform"<if condition="!is_browser('webtv')"> onsubmit="return (vB_Editor['$editorid'].prepare_submit(this.subject.value, $vboptions[postminchars]) && validateAd(this));"</if>>