title: Extjs4 chart not plotting correct data
body: <p>I created a simple line chart in Extjs4 for one of my projects, and the chart is not plotting the right data. </p>
  
  <p><img src="https://i.stack.imgur.com/XGb9u.png" alt="enter image description here"></p>
  
  <p>The chart uses the same store as the grid, but not showing the same data. Is there any way to trace the source of the problem, if not fixing it altogether?</p>
  
  <p>The following is the code I use to generate the chart.</p>
  
  <pre><code>{
      xtype: 'chart',
      animate: true,
      shadow: true,
      store: 'Dataalls',
      legend: {
          position: 'top'
      },
      axes: [{
          type: 'Numeric',
          position: 'left',
          title: 'Wind Speed',
          fields: ['windspeed'],
          grid: true
      }, {
          type: 'Category',
          position: 'bottom',
          title: 'Time',
          fields: ['time']
      }],
      series: [{
          type: 'line',
          axis: 'left',
          xField: ['time'],
          yField: ['windspeed']
      }]
  }
  </code></pre>
  
  <p>(I tried using type: 'Time' for the x axis but gets the error "date.getFullYear is not a function" )</p>