title: Fail to Render Line Chart in EXTJS 4 if Using Ext.data.Store with Proxy
body: <p>I have problem rendering Line Chart in EXTJS 4. I have Viewport that contain accordion Layout. In that layout, I create very simple Chart.</p>
  
  <p>Here is my code:</p>
  
  <pre class="lang-js prettyprint-override"><code>var chartBox = Ext.create('Ext.chart.Chart', {
      width: 500,
      height: 300,
      style: 'background:#fff',
      animate: true,
      store: Ext.data.Store({
          fields: ['active'],
          data: [
              { 'name': 'Jan 2011',   'active': 10},
              { 'name': 'Feb 2011',   'active': 9},
              { 'name': 'Mar 2011',   'active': 13},
              { 'name': 'Apr 2011',   'active': 5},
              { 'name': 'Mei 2011',   'active': 17},
          ]
      }),
      theme: 'Category1',
      legend: {
          position: 'right'
      },
      axes: [{
          type: 'Numeric',
          position: 'left',
          fields: ['active'],
          label: {
              renderer: Ext.util.Format.numberRenderer('0,0')
          },
          title: 'Total',
          grid: true,
          minimum: 0
      },{
          type: 'Category',
          position: 'bottom',
          fields: ['name'],
          title: 'Month and Year'
      }],
      series: [{
          type: 'line',
          highlight: {
              size: 7,
              radius: 7
          },
          axis: 'left',
          xField: 'name',
          yField: 'active',
          markerConfig: {
              type: 'cross',
              size: 4,
              radius: 4,
              'stroke-width': 0
          }
      }]
  })
  </code></pre>
  
  <p>Then, it is work. See this screenshot.</p>
  
  <p><img src="https://i.stack.imgur.com/ZRSOy.png" alt="Render Line Chart EXTJS 4 correct!"></p>
  
  <p>But after I change this part of code:</p>
  
  <pre class="lang-js prettyprint-override"><code>store: Ext.data.Store({
      fields: ['active'],
      data: [
          { 'name': 'Jan 2011',   'active': 10},
          { 'name': 'Jan 2011',   'active': 10},
          { 'name': 'Jan 2011',   'active': 10},
          { 'name': 'Jan 2011',   'active': 10},
          { 'name': 'Jan 2011',   'active': 10},
      ]
  }),
  </code></pre>
  
  <p>with this:</p>
  
  <pre class="lang-js prettyprint-override"><code>store: Ext.data.Store({
      fields: ['active'],
      autoLoad: true,
      proxy: {
          type: 'ajax',
          url : 'data/statexample_noroot.json',
          reader: {
              type: 'json'
          }
      }
  }),
  </code></pre>
  
  <p>to load data from Server, it is not work. See this screenshot. </p>
  
  <p><img src="https://i.stack.imgur.com/2DRtU.png" alt="Rendering Line Chart EXTJS 4  failed!"></p>
  
  <p>This is the content from "statexample_noroot.json" :</p>
  
  <pre class="lang-js prettyprint-override"><code>[
      { 'name': 'Jan 2011',   'active': 10},
      { 'name': 'Feb 2011',   'active': 9},
      { 'name': 'Mar 2011',   'active': 13},
      { 'name': 'Apr 2011',   'active': 5},
      { 'name': 'Mei 2011',   'active': 17},
  ]
  </code></pre>
  
  <p>I only get false rendering Line Chart with warning "Unexpected value NaN parsing x attribute.", "Unexpected value NaN parsing width attribute.", "Unexpected value matrix(NaN,0,NaN,1,NaN,0) parsing transform attribute." etc....</p>
  
  <p>I have set axes with Numeric. I try everything include using Ext.data.Model, Ext.data.JsonStore, but still didn't work.</p>
  
  <p>What is the difference?? What I am missing here? Anyone know why this thing happen? I am stuck for plenty of hours.</p>