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I've just started learning Cloudmade Web Maps API. I'm at marker clustering, and I'm facing a strange problem; whenever I try accessing the page below, content of elements must consist of well-formed character... trace is shown, and the map doesn't render. My code is shown below:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "">
<html xmlns="" xml:lang="en">
  <script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<title>CloudMade Marker Clustering</title>

<div id="cm-example" style="width: 500px; height: 500px"></div>

<script type="text/javascript">
  var cloudmade = new CM.Tiles.CloudMade.Web({key: 'API-KEY'});
  var map = new CM.Map('cm-example', cloudmade);

  map.setCenter(new CM.LatLng(51.50874, 22.76367), 4);

  var markers = [];
  for (var i = 0; i < samplePoints.length; i++) {
    markers.push(new CM.Marker(new CM.LatLng(samplePoints[i][0], samplePoints[i][1])));

  var clusterer = new CM.MarkerClusterer(map, {clusterRadius: 70});


It appears simple, but I can't spot the problem. Any assistance will be appreciated. Thanks in advance.

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