title: Why is the data in this ExtJS grid not showing?
body: <p>I've isolated the checkbox grid from <a href="http://dev.sencha.com/deploy/dev/examples/grid/grid-plugins.js" rel="nofollow noreferrer">this example of ExtJS grids</a> into the following code.</p>
  
  <p>It shows the grid with the headers but not the data:</p>
  
  <p><img src="https://i.stack.imgur.com/HpU1V.png" alt="enter image description here"></p>
  
  <p>Firebug shows no Javascript errors.</p>
  
  <p><strong>What do I have to do to get the dummy data to show in the grid?</strong></p>
  
  <pre><code>Ext.onReady(function(){
  
      Ext.QuickTips.init();
  
      var xg = Ext.grid;
  
      var reader = new Ext.data.ArrayReader({}, [
          {name: 'company'},
          {name: 'price', type: 'float'},
          {name: 'change', type: 'float'},
          {name: 'pctChange', type: 'float'},
          {name: 'lastChange', type: 'date', dateFormat: 'n/j h:ia'},
          {name: 'industry'},
          {name: 'desc'}
      ]);
  
      var sm = new xg.CheckboxSelectionModel();
  
      var grid2 = new xg.GridPanel({
          store: new Ext.data.Store({
              reader: reader,
              data: xg.dummyData
          }),
          cm: new xg.ColumnModel({
              defaults: {
                  width: 120,
                  sortable: true
              },
              columns: [
                  sm,
                  {id:'company',header: "Company", width: 200, dataIndex: 'company'},
                  {header: "Price", renderer: Ext.util.Format.usMoney, dataIndex: 'price'},
                  {header: "Change", dataIndex: 'change'},
                  {header: "% Change", dataIndex: 'pctChange'},
                  {header: "Last Updated", width: 135, renderer: Ext.util.Format.dateRenderer('m/d/Y'), dataIndex: 'lastChange'}
              ]
          }),
          sm: sm,
          columnLines: true,
          width:800,
          height:300,
          frame:true,
          title:'Framed with Checkbox Selection and Horizontal Scrolling',
          iconCls:'icon-grid',
          renderTo: document.body
      });
  
      Ext.grid.dummyData = [
          ['3m Co',71.72,0.02,0.03,'9/1 12:00am', 'Manufacturing'],
          ['Alcoa Inc',29.01,0.42,1.47,'9/1 12:00am', 'Manufacturing'],
          ['Altria Group Inc',83.81,0.28,0.34,'9/1 12:00am', 'Manufacturing'],
          ['American Express Company',52.55,0.01,0.02,'9/1 12:00am', 'Finance'],
          ['American International Group, Inc.',64.13,0.31,0.49,'9/1 12:00am', 'Services'],
          ['AT&amp;T Inc.',31.61,-0.48,-1.54,'9/1 12:00am', 'Services'],
          ['Boeing Co.',75.43,0.53,0.71,'9/1 12:00am', 'Manufacturing'],
          ['Caterpillar Inc.',67.27,0.92,1.39,'9/1 12:00am', 'Services'],
          ['Citigroup, Inc.',49.37,0.02,0.04,'9/1 12:00am', 'Finance'],
          ['E.I. du Pont de Nemours and Company',40.48,0.51,1.28,'9/1 12:00am', 'Manufacturing'],
          ['Exxon Mobil Corp',68.1,-0.43,-0.64,'9/1 12:00am', 'Manufacturing'],
          ['General Electric Company',34.14,-0.08,-0.23,'9/1 12:00am', 'Manufacturing'],
          ['General Motors Corporation',30.27,1.09,3.74,'9/1 12:00am', 'Automotive'],
          ['Hewlett-Packard Co.',36.53,-0.03,-0.08,'9/1 12:00am', 'Computer'],
          ['Honeywell Intl Inc',38.77,0.05,0.13,'9/1 12:00am', 'Manufacturing'],
          ['Intel Corporation',19.88,0.31,1.58,'9/1 12:00am', 'Computer'],
          ['International Business Machines',81.41,0.44,0.54,'9/1 12:00am', 'Computer'],
          ['Johnson &amp; Johnson',64.72,0.06,0.09,'9/1 12:00am', 'Medical'],
          ['JP Morgan &amp; Chase &amp; Co',45.73,0.07,0.15,'9/1 12:00am', 'Finance'],
          ['McDonald\'s Corporation',36.76,0.86,2.40,'9/1 12:00am', 'Food'],
          ['Merck &amp; Co., Inc.',40.96,0.41,1.01,'9/1 12:00am', 'Medical'],
          ['Microsoft Corporation',25.84,0.14,0.54,'9/1 12:00am', 'Computer'],
          ['Pfizer Inc',27.96,0.4,1.45,'9/1 12:00am', 'Services', 'Medical'],
          ['The Coca-Cola Company',45.07,0.26,0.58,'9/1 12:00am', 'Food'],
          ['The Home Depot, Inc.',34.64,0.35,1.02,'9/1 12:00am', 'Retail'],
          ['The Procter &amp; Gamble Company',61.91,0.01,0.02,'9/1 12:00am', 'Manufacturing'],
          ['United Technologies Corporation',63.26,0.55,0.88,'9/1 12:00am', 'Computer'],
          ['Verizon Communications',35.57,0.39,1.11,'9/1 12:00am', 'Services'],
          ['Wal-Mart Stores, Inc.',45.45,0.73,1.63,'9/1 12:00am', 'Retail'],
          ['Walt Disney Company (The) (Holding Company)',29.89,0.24,0.81,'9/1 12:00am', 'Services']
      ];
  
  });
  </code></pre>