agregar markers con openlayers

gistfile1.js

var size = new OpenLayers.Size(21,25);
var offset = new OpenLayers.Pixel(-(size.w/2), -size.h);
var icon = new OpenLayers.Icon("http://google-maps-icons.googlecode.com/files/arch.png", size, offset);
var zoom, center, currentPopup, map, lyrMarkers;
var popupClass = OpenLayers.Class(OpenLayers.Popup.FramedCloud, {
				    "autoSize": true,
				    "minSize": new OpenLayers.Size(300, 50),
				    "maxSize": new OpenLayers.Size(500, 300),
				    "keepInMap": true
				  });
var bounds = new OpenLayers.Bounds();

function addMarker(lng, lat, info) {
  var pt = new OpenLayers.LonLat(lng, lat)
    .transform(new OpenLayers.Projection("EPSG:4326"), 
               map.getProjectionObject());
  bounds.extend(pt);
  var feature = new OpenLayers.Feature(lyrMarkers, pt);
  feature.closeBox = true;
  feature.popupClass = popupClass;
  feature.data.popupContentHTML = info;
  feature.data.overflow = "auto";
  var marker = new OpenLayers.Marker(pt, icon.clone());
  var markerClick = function(evt) {
    if (currentPopup != null && currentPopup.visible()) {
      currentPopup.hide();
    }
    if (this.popup == null) {
      this.popup = this.createPopup(this.closeBox);
      map.addPopup(this.popup);
      this.popup.show();
    } else {
      this.popup.toggle();
    }
    currentPopup = this.popup;
    OpenLayers.Event.stop(evt);
  };
  marker.events.register("mousedown", feature, markerClick);
  lyrMarkers.addMarker(marker);
}