title: json array does not show in extjs grid
body: <p>I use the following Ext function for bind the values in ext grid from the json array.I get the the json array from the URL.It will work Fine,which means i get the values.And my problem is If i try to <strong>bind the values in Extjs grid i cant able to add the json array values in that grid</strong>.How to solve this?</p>
  
  <pre><code>Ext.onReady(function(){
  
      var proxy=new Ext.data.HttpProxy({url:'http://someurl'});
  
      var reader=new Ext.data.JsonReader({},[
            {name: 'User_Id', mapping: 'User_Id'},
            {name: 'First_Name', mapping: 'First_Name'},            
            {name: 'Last_Name', mapping: 'Last_Name'}, 
            {name: 'Notes', mapping: 'Notes'} 
       ]);
       //alert(reader);
       var store=new Ext.data.Store(    {
           proxy:proxy,
           reader:reader
       });
  
      store.load();
  
  
      // create the grid
      var grid = new Ext.grid.GridPanel({
          store: store,
          columns: [
              {header: "User_Id", width: 60, dataIndex: 'User_Id', sortable: true},
              {header: "First_Name", width: 60, dataIndex: 'First_Name', sortable: true},
              {header: "Last_Name", width: 60, dataIndex: 'Last_Name', sortable: true},
                             {header: "Notes", width:80, dataIndex: 'Notes', sortable: true}
  
          ],
          renderTo:'example-grid',
          width:2000,
          height:1000
      });
  
  });
  </code></pre>