title: extjs4 radar chart bug?
body: <p>I wrote a demo using the radar chart example in extjs4.1 doc. </p>
  
  <p>And it worked well.</p>
  
  <p>But after I wrote the server-side action for it, the radar chart missed its labels and the radius lines. </p>
  
  <p>Is this a bug of radar chart in extjs4.1?</p>
  
  <ol>
  <li><p>worked well</p>
  
  <pre><code>var store = Ext.create('Ext.data.JsonStore', {
      fields: ['name', 'data1', 'data2'],
      data: [
          { 'name': 'metric one',   'data1': 14, 'data2': 12 },
          { 'name': 'metric two',   'data1': 16, 'data2':  8 },
          { 'name': 'metric three',   'data1': 10, 'data2':  10}
      ]
  });
  </code></pre></li>
  <li><p>missed labels and radius lines</p>
  
  <pre><code>var store = Ext.create('Ext.data.JsonStore', {
      fields: ['name', 'data1', 'data2'],
      proxy:{
         type:'ajax',
         url:'radarChart.json'
      },
      autoLoad:true    
  });
  </code></pre></li>
  </ol>