title: treegrid example doesn't work
body: <p>I'm trying to run the treegrid example but it only gives me the grid with no data in it!</p>
  
  <p>this is my default.aspx:</p>
  
  <pre><code>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"&gt;
  &lt;html&gt;
  &lt;head&gt;
      &lt;meta http-equiv="Content-Type" content="text/html; charset=utf-8" /&gt;
      &lt;title&gt;My tree grid&lt;/title&gt;
  
  &lt;!-- Ext --&gt;
  &lt;link rel="stylesheet" type="text/css" href="ExtJs4/resources/css/ext-all.css" /&gt;
  &lt;script type="text/javascript" src="ExtJs4/bootstrap.js"&gt;&lt;/script&gt;
  &lt;script type="text/javascript" src="ExtJs4/ext-all.js"&gt;&lt;/script&gt;
  
  
  &lt;!-- example code --&gt;
  
  &lt;script type="text/javascript" src="Scripts/treepanel.js"&gt;&lt;/script&gt;
  
  &lt;/head&gt;
  &lt;body&gt;
  
  &lt;h1&gt;My tree grid&lt;/h1&gt;
  
  &lt;div id="tree-div"&gt; &lt;/div&gt;
  </code></pre>
  
  <p>
  </p>
  
  <p>this is my treepanel.js</p>
  
  <pre><code>Ext.Loader.setConfig({ enabled: true }); //
  
  Ext.Loader.setPath('Ext.ux', '../ux');
  
  Ext.require([
      'Ext.tip.QuickTipManager',
      'Ext.container.Viewport',
      'Ext.layout.*',
      'Ext.form.Panel',
      'Ext.form.Label',
      'Ext.grid.*',
      'Ext.data.*',
      'Ext.tree.*',
      'Ext.selection.*',
      'Ext.tab.Panel'
  ]);
  
  Ext.onReady(function () 
  {
   Ext.define('Task', {
      extend: 'Ext.data.Model',
      fields: [
          {name: 'task',     type: 'string'},
          {name: 'user',     type: 'string'},
          {name: 'duration', type: 'string'}
      ] 
  });
  
  var store = Ext.create('Ext.data.TreeStore', {
      model: 'Task',
      proxy: {
          type: 'ajax',
  
          url: 'treegrid.json'////
      },
      folderSort: true
  });
  
  //Ext.ux.tree.TreeGrid is no longer a Ux. You can simply use a tree.TreePanel
  var tree = Ext.create('Ext.tree.Panel', {
      title: 'Core Team Projects',
      width: 500,
      height: 300,
      renderTo: 'tree-div', 
      rootVisible:true,
      store: store,
      autoload:true,
      columns: [{xtype: 'treecolumn',  text: 'Task',   dataIndex: 'task' },{text: 'Assigned To', dataIndex: 'user'}]
  });
  
  });
  </code></pre>
  
  <p>am I doing something wrong here?
  I have no error msg from my firebug...so why isn't it working?</p>
  
  <p>if I can't run an example how am I going to do more..I'm frustrated with this.</p>