JavaScript - Ayuda con markers en Google Maps V2

<script type="text/javascript">

    document.write('<script type="text/javascript" src="popupmarker'+(document.location.search.indexOf('packed')>-1?'_packed':'')+'.js"><'+'/script>');

  </script>

<script type="text/javascript">

    //<![CDATA[

    var iconBlue = new GIcon();

    iconBlue.image = 'mm_20_blue.png';

    iconBlue.shadow = 'mm_20_shadow.png';

    iconBlue.iconSize = new GSize(12, 20);

    iconBlue.shadowSize = new GSize(22, 20);

    iconBlue.iconAnchor = new GPoint(6, 20);

    iconBlue.infoWindowAnchor = new GPoint(5, 1);

    var iconRed = new GIcon();

    iconRed.image = 'mm_20_red.png';

    iconRed.shadow = 'mm_20_shadow.png';

    iconRed.iconSize = new GSize(12, 20);

    iconRed.shadowSize = new GSize(22, 20);

    iconRed.iconAnchor = new GPoint(6, 20);

    iconRed.infoWindowAnchor = new GPoint(5, 1);

    var customIcons = [];

    customIcons["restaurant"] = iconBlue;

    customIcons["bar"] = iconRed;

    function load() {

      if (GBrowserIsCompatible()) {

        var map = new GMap2(document.getElementById("map"));

        map.addControl(new GSmallMapControl());

        map.addControl(new GMapTypeControl());

        map.setCenter(new GLatLng(-27.366667, -70.333333), 5);

        // Change this depending on the name of your PHP file

        GDownloadUrl("phpsqlajax_genxml.php", function(data) {

          var xml = GXml.parse(data);

          var markers = xml.documentElement.getElementsByTagName("marker");

          for (var i = 0; i < markers.length; i++) {

            var name = markers[i].getAttribute("name");

 var opts = {

          text : "Volcan " + name

        };

        var marker = new PopupMarker(new GLatLng(parseFloat(markers[i].getAttribute("lat")), parseFloat(markers[i].getAttribute("lng"))), opts);

        map.addOverlay(marker);

            var address = markers[i].getAttribute("address");

            var type = markers[i].getAttribute("type");

            var point = new GLatLng(parseFloat(markers[i].getAttribute("lat")),

                                    parseFloat(markers[i].getAttribute("lng")));

            var marker = createMarker(point, name, address, type);

            map.addOverlay(marker);

          }

        });

      }

    }

    function createMarker(point, name, address, type) {

      var marker = new GMarker(point, customIcons[type]);

      var html = "<b>Volcan " + name + "</b> <br/>" + "<p>Dispone de la siguiente infomacion:</p>" + address + "<li><a>Informacion General</a></li><li>Informacion Eruptiva Moderna</li><li>Vulcanologia Fisica</li><li>Geoquimica de Rocas</li><li>Geoquimica de Fluidos</li><li>Edades</li><li>Mapa geoligico</li><br><br/>";

      GEvent.addListener(marker, 'click', function() {

        marker.openInfoWindowHtml(html);

      });

      return marker;

    }

    //]]>

  </script>