heatmap isn't working

I followed a sample code to create a fusion tables map with 'heatmap' (hotspots as I called it) but it's not working. Could someone take a look on it, please?

I don't know whether the problem is with some syntax element (but the code didn't break) or with the form element? Another possibility could be that there are just a few points, and it's not possible to produce a heatmap only with that points. But I never heard of such a technical issue.

<!DOCTYPE html>
<html>
<head>
  <style>
    #map-canvas { width:500px; height:400px; }
  </style>
  <script type="text/javascript"
    src="http://maps.google.com/maps/api/js?sensor=false">
  </script>
  <script type="text/javascript">
    var map;
    var layerl0;
    function initialize() {
      map = new google.maps.Map(document.getElementById('map-canvas'), {
        center: new google.maps.LatLng(0, 0),
        zoom: 4,
        mapTypeId: google.maps.MapTypeId.ROADMAP
      });
      layerl0 = new google.maps.FusionTablesLayer({
        query: {
          select: "'ENDERECO_GOOGLE'",
          from: 3767057
        },
        map: map
      });
      google.maps.event.addDomListener(document.getElementById('heatmap'),
        'click', function() {
         var heatmap = document.GetElementById('heatmap');
         layer.setOptions({
           heatmap: {
             enabled: heatmap.checked
           }
         });
      });           
    }
    google.maps.event.addDomListener(window, 'load', initialize);
  </script>
</head>
<body>
  <div id="map-canvas"></div>
  <div>
    <input id="heatmap" type="checkbox" />
    <label>Hotspots</label>
  </div>   
</body>
</html>

Solution

You've got 2 syntax errors in the file you posted.

document.GetElementById();
// must be
document.getElementById();

and

layer.setOptions()
// must be
layerl0.setOptions()