title: Google Maps API Store Locator example with MarkerClusterer
body: <p>I recently created a store locator using the "Google Maps API Store Locator" <a href="http://code.google.com/apis/maps/articles/phpsqlsearch.html#createmap" rel="nofollow">example</a>.</p>
  
  <p>Now I'm trying to implement the <a href="http://gmaps-utility-library.googlecode.com/svn/trunk/markerclusterer/1.0/docs/reference.html" rel="nofollow">MarkerClusterer Library</a> so that I can display a large single marker instead of multiple markers when users are zoomed out at a certain distance.</p>
  
  <p>When I add the output code:</p>
  
  <pre><code>... 
  
  GDownloadUrl(searchUrl, function(data) {
  
  var xml = GXml.parse(data);
  
  var markers = xml.documentElement.getElementsByTagName('marker');
  
  map.clearOverlays();
  
  var markerCluster = new MarkerClusterer(map, markers);
  
  ...
  </code></pre>
  
  <p>I get the following error:</p>
  
  <blockquote>
    <p>marker.getLatLng is not a function</p>
  </blockquote>
  
  <p>Has anyone tried to implement this piece in the past?</p>