jQuery .index() returns a negative number
<p>Maybe it is just a simple mistake but this thing is driving me crazy.
I want to know why the hell this jQuery line is returning <strong>-1</strong>?</p>

<pre><code>$('td[class!="traco"]:last').index('td.diaNormal')
</code></pre>

<p>First of all, when this function returns a negative number? Why does it happen?
Thank you all in advance, Fernando.</p>

<hr>

<p>EDIT:</p>

<p>The most intersting thing is that my page has the element i am looking for, and the
jQuery index just returns -1.</p>

<hr>

<p>EDIT2:
This is my HTML, <a href="http://jsfiddle.net/bv7SU/" rel="nofollow">http://jsfiddle.net/bv7SU/</a></p>
