title: jQuery is not finding elements
body: <p>jQuery is not finding any elements. <code>alert($("#testbutton").length);</code> displays 0 every time. </p>
  
  <p>Am I doing something wrong?</p>
  
  <p><strong>My JS / jQuery code:</strong></p>
  
  <pre><code>(function ($) {
      alert($("#testbutton").length);
  }) (jQuery);
  </code></pre>
  
  <p><strong>My HTML:</strong></p>
  
  <pre><code>&lt;html&gt;
      &lt;body&gt;
          &lt;div id="header"&gt;
              &lt;div class="button" id="testbutton"&gt;Test&lt;/div&gt;
          &lt;/div&gt;
      &lt;/body&gt;    
  &lt;/html&gt;
  </code></pre>