OpenLayers 标记图标问题

我正在我的网站中创建 OSM 地图，并使用 openlayer 添加一些标记。我的问题是我总是得到相同的标记图标。

 <script type="text/javascript">

 var map = new OpenLayers.Map("heatMap");
    var mapnik = new OpenLayers.Layer.OSM();
    map.addLayer(mapnik);
    map.setCenter(new OpenLayers.LonLat(-4.0575942987957,54.390175926091) // Center of the map
      .transform(
        new OpenLayers.Projection("EPSG:4326"), // transform from WGS 1984
        new OpenLayers.Projection("EPSG:900913") // to Spherical Mercator Projection
      ), 6 // Zoom level
    );

    var markers = new OpenLayers.Layer.Markers( "Markers" );
    map.addLayer(markers);

    var icon1 = new OpenLayers.Icon('http://www.openlayers.org/dev/img/marker.png', size, offset);
    var icon2 = new OpenLayers.Icon('http://www.openlayers.org/dev/img/marker-gold.png', size, offset);
    var icon3 = new OpenLayers.Icon('http://www.openlayers.org/dev/img/marker-green.png', size, offset);

    var lonLat1 = new OpenLayers.LonLat(-4.0575942987957,54.390175926091).transform(
                            new OpenLayers.Projection("EPSG:4326"), // transform from WGS 1984
                            map.getProjectionObject() // to Spherical Mercator Projection
                            );

    var lonLat2 = new OpenLayers.LonLat(-3.0575942987957,54.390175926091).transform(
                            new OpenLayers.Projection("EPSG:4326"), // transform from WGS 1984
                            map.getProjectionObject() // to Spherical Mercator Projection
                            );

    var lonLat3 = new OpenLayers.LonLat(-5.0575942987957,54.390175926091).transform(
                            new OpenLayers.Projection("EPSG:4326"), // transform from WGS 1984
                            map.getProjectionObject() // to Spherical Mercator Projection
                            );

    var marker1 = new OpenLayers.Marker(lonLat1);
    var feature = new OpenLayers.Feature(markers, lonLat);
    feature.closeBox = true;
    feature.popupClass = OpenLayers.Class(OpenLayers.Popup.AnchoredBubble, { autoSize: true });
    feature.data.popupContentHTML = '<p>Marker1<p>';
    feature.data.overflow = "hidden";

    marker1.feature = feature;

    var markerClick = function (evt) {
        if (this.popup == null) {
            this.popup = this.createPopup(this.closeBox);
            map.addPopup(this.popup);
            this.popup.show();
        } else {
            this.popup.toggle();
        }
        OpenLayers.Event.stop(evt);
    };
    marker1.events.register("mousedown", feature, markerClick);

    var marker2 = new OpenLayers.Marker(lonLat2);
    var feature = new OpenLayers.Feature(markers, lonLat);
    feature.closeBox = true;
    feature.popupClass = OpenLayers.Class(OpenLayers.Popup.AnchoredBubble, { autoSize: true });
    feature.data.popupContentHTML = '<p>Marker2<p>';
    feature.data.overflow = "hidden";

    marker2.feature = feature;

    var markerClick = function (evt) {
        if (this.popup == null) {
            this.popup = this.createPopup(this.closeBox);
            map.addPopup(this.popup);
            this.popup.show();
        } else {
            this.popup.toggle();
        }
        OpenLayers.Event.stop(evt);
    };
    marker2.events.register("mousedown", feature, markerClick);

    var marker3 = new OpenLayers.Marker(lonLat3);
    var feature = new OpenLayers.Feature(markers, lonLat);
    feature.closeBox = true;
    feature.popupClass = OpenLayers.Class(OpenLayers.Popup.AnchoredBubble, { autoSize: true });
    feature.data.popupContentHTML = '<p>Marker 3<p>';
    feature.data.overflow = "hidden";

    marker3.feature = feature;

    var markerClick = function (evt) {
        if (this.popup == null) {
            this.popup = this.createPopup(this.closeBox);
            map.addPopup(this.popup);
            this.popup.show();
        } else {
            this.popup.toggle();
        }
        OpenLayers.Event.stop(evt);
    };
    marker3.events.register("mousedown", feature, markerClick);

    markers.addMarker(marker1, icon1);

    markers.addMarker(marker2, icon2);

    markers.addMarker(marker3, icon3);

现在的问题是所有三个标记都有相同的图标...有人可以帮助我..

创建标记实例后更改图标。

marker = new ....
var size = new OpenLayers.Size(25, 12);
var offset = new OpenLayers.Pixel(-(size.w / 2), -size.h);
marker.icon = new OpenLayers.Icon("marker.png", size, offset);
//UPDATE AGAIN
marker.icon.size = size;
marker.icon.offset = offset;
marker.draw();