title: can't use addChild method
body: <p>I'm using the dynatree plugin for the first time, and I'm trying to add nodes dynamically.
  My code is below:</p>
  
  <pre><code>function DrawTree() {
   var names = GetChildName();  
   var rootNode = $("#ProcessRoleTree").dynatree("getRoot");
   var childNode = rootNode.addChild({ title: names[0].Name });
  }
  </code></pre>
  
  <p>On runtime an error displays</p>
  
  <blockquote>
    <p>Microsoft JScript runtime error: Object doesn't support this property or method</p>
  </blockquote>
  
  <p>Am I missing something ??
  I have verify that i included needed libraries :</p>
  
  <pre><code>&lt;script src="Jquery/jquery/jquery.js" type="text/javascript"&gt;&lt;/script&gt;
  &lt;script src="Jquery/jquery/jquery-ui.custom.js" type="text/javascript"&gt;&lt;/script&gt;
  &lt;script src="Jquery/jquery/jquery.cookie.js" type="text/javascript"&gt;&lt;/script&gt;
  
  &lt;link href="Jquery/src/skin-vista/ui.dynatree.css" rel="stylesheet" type="text/css" /&gt;
  &lt;script src="Jquery/src/jquery.dynatree.js" type="text/javascript"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>Thanks in advance! </p>