Jquery Error: $("[data-weight]") is null
<p>Stripped a ton of stuff to make it more readable, it throws an error on the line:</p>

<pre><code>$('[data-weight]').each(function() {
</code></pre>

<p>Saying that it is null</p>

<pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 
    1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"&gt;

    &lt;html xmlns="http://www.w3.org/1999/xhtml" &gt;
    &lt;head id="ctl00_mainHead"&gt;

        &lt;script type="text/javascript" src="includes/jqueryv1.4.2.js"&gt;&lt;/script&gt;

           &lt;script type="text/javascript"&gt;
            jQuery(document).ready(function() {
                $('[data-weight]').each(function() {

                    var usingMetric = false;

                    var $this = $(this);
                    var value = $this.attr("data-weight");
                    if (usingMetric) {
                        $this.text(value + " KG");
                    }
                    else {
                        value = parseFloat(value) * 2.20462262; // Convert to imperial
                        $this.text(value + " lbs");
                    }
                });
            });
        &lt;/script&gt;
     &lt;/head&gt;

    &lt;body&gt;

    &lt;form name="aspnetForm" method="post" action="viewProduct.aspx?ID=3&amp;amp;action=added" id="aspnetForm"&gt;


        &lt;div class="productDetail"&gt;
            &lt;b&gt;Product Details&lt;/b&gt;
        &lt;/div&gt;

        &lt;strong data-weight="200"&gt;800 KG&lt;/strong&gt;


&lt;/form&gt;
    &lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p><strong>Update</strong></p>

<p>It's a follow on my this question:</p>

<p><a href="http://stackoverflow.com/questions/3749900/using-javascript-to-display-weights">http://stackoverflow.com/questions/3749900/using-javascript-to-display-weights</a></p>
