Area charts behaving like line charts

// Use Morris.Area instead of Morris.Line
Morris.Area({
  element: 'graph',
  behaveLikeLine: true,
  data: [
    {x: '2011 Q1', y: 3, z: 3},
    {x: '2011 Q2', y: 2, z: 1},
    {x: '2011 Q3', y: 2, z: 4},
    {x: '2011 Q4', y: 3, z: 3}
  ],
  xkey: 'x',
  ykeys: ['y', 'z'],
  labels: ['Y', 'Z']
});