title: Google Maps API v3 Heatmaps Error: "Cannot read property 'HeatmapLayer' of undefined"
body: <p>I am trying to load a Heatmaps layer onto my google maps, but for some reason I just keep getting the error "Cannot read property 'HeatmapLayer' of undefined." </p>
  
  <pre><code>map = new google.maps.Map(document.getElementById("gmaps"),{
      zoom: 11,
      center: new google.maps.LatLng(39.788403, -86.19990800000001),
      mapTypeControl: false,
      streetViewControl: false,
      mapTypeId: google.maps.MapTypeId.ROADMAP,
      panControl: false
  });
  
  heatMapData = [
  new google.maps.LatLng(39.77745056152344, -86.10900878906250),
  new google.maps.LatLng(39.82060623168945, -86.17008972167969),
  new google.maps.LatLng(39.77947616577148, -86.17008972167969),
  new google.maps.LatLng(39.82987594604492, -86.13955688476562),
  new google.maps.LatLng(39.74195098876953, -86.12429046630860)
  ];
  heatmap = new google.maps.visualization.HeatmapLayer({
      data: heatMapData,
      map: map
  });
  </code></pre>
  
  <p>Here is the jsFiddle: <a href="http://jsfiddle.net/9HQ2a/3/" rel="noreferrer">http://jsfiddle.net/9HQ2a/3/</a></p>