Draw Graphs from database using Morris charts in ASP.Net

when i am passing dynamic data like below it does not show the Line chart, can any body help me.

http://morrisjs.github.io/morris.js/lines.html

$.ajax({
      type: "POST",
      dataType: 'json',
      async: false,
      url: "wfDashboard.aspx/BindChart",
      cache: false,
      data: '{}',
      contentType: "application/json; charset=utf-8",
      success: function (msg) {
      var source= msg.d._DESC
      Morris.Line({
            element: 'line-example',
            data: source,
            xkey: 'Date',
            ykeys: ['A', 'B', 'C'],
            labels: ['XYZ', 'ABC', 'PQR'],
            lineColors: ['#0aa699']
       });
    }
});

 and my source look like

source=[{'Date':'2014-8','A':'6500.00','B':'6566.00','C':'561265.00'},
{'Date':'2014-9','A':'10000.00','B':'14000.00','C':'459434.00'}]

 When i hard-code the same data in morris line chart its work fine

Morris.Line({
   element: 'line-example',
   data: [{'Date':'2014-8','A':'6500.00','B':'6566.00','C':'561265.00'},
                      {'Date':'2014-9','A':'10000.00','B':'14000.00','C':'459434.00'}],
   xkey: 'Date',
   ykeys: ['A', 'B', 'C'],
   labels: ['XYZ', 'ABC', 'PQR'],
   lineColors: ['#0aa699']
});