openlayers在firefox中的问题

我把openlayers中的案例copy出来修改后执行了一下，在ie中没有任何问题，各种好使。换到firefox中就出现openlayers.Style is not a constructor、openlayers.request is undefined 等错误，请问这是怎么回事儿？

以下是代码
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>OpenLayers StyleMap</title>
    <link rel="stylesheet" href="theme/default/style.css" type="text/css" />
    <link rel="stylesheet" href="style.css" type="text/css" />
    <script src="lib/OpenLayers.js"></script>
    <script type="text/javascript">
        var map;

        function init() {
            map = new OpenLayers.Map('map');
            var wms = new OpenLayers.Layer.WMS(
                "OpenLayers WMS",
                "http://vmap0.tiles.osgeo.org/wms/vmap0",
                {layers: 'basic'}
            );

            // Create 50 random features, and give them a "type" attribute that
            // will be used to style them by size.
            var features = new Array(50);
            for (var i=0; i<features.length; i++) {
                features[i] = new OpenLayers.Feature.Vector(
                    new OpenLayers.Geometry.Point(
                        (360 * Math.random()) - 180, (180 * Math.random()) - 90
                    ), {
                        type: 5 + parseInt(5 * Math.random())
                    }
                );
            }

            // Create a styleMap to style your features for two different
            // render intents.  The style for the 'default' render intent will
            // be applied when the feature is first drawn.  The style for the
            // 'select' render intent will be applied when the feature is
            // selected.
            var myStyles = new OpenLayers.StyleMap({
                "default": new OpenLayers.Style({
                    pointRadius: "${type}", // sized according to type attribute
                    fillColor: "#ffcc66",
                    strokeColor: "#ff9933",
                    strokeWidth: 2,
                    graphicZIndex: 1
                }),
                "select": new OpenLayers.Style({
                    fillColor: "#66ccff",
                    strokeColor: "#3399ff",
                    graphicZIndex: 2
                })
            });

            // Create a vector layer and give it your style map.
            var points = new OpenLayers.Layer.Vector("Points", {
                styleMap: myStyles,
                rendererOptions: {zIndexing: true}
            });
            points.addFeatures(features);
            map.addLayers([wms, points]);

            // Create a select feature control and add it to the map.
            var select = new OpenLayers.Control.SelectFeature(points, {hover: true});
            map.addControl(select);
            select.activate();

            map.setCenter(new OpenLayers.LonLat(0, 0), 1);
        }
    </script>
  </head>

  <body onload="init()">
    <h1 id="title">StyleMap Example</h1>

    <div id="tags"></div>

    <p id="shortdesc">
        Shows how to use a StyleMap to style features with rule based styling.
        A style map references on or more OpenLayers.Style objects.  These
        OpenLayers.Style objects are collections of OpenLayers.Rule objects
        that determine how features are styled.  An OpenLayers.Rule object
        combines an OpenLayers.Filter object with a symbolizer.  A filter is used
        to determine whether a rule applies for a given feature, and a symbolizer
        is used to draw the feature if the rule applies.
    </p>

    <div id="map" class="smallmap"></div>

    <div id="docs">
        <p>A style map is used with vector layers to define styles for various
        rendering intents.  The style map used here has styles defined for the
        "default" and "select" rendering intents.  This map also has an active
        select feature control.  When you hover over features, they are selected
        and drawn with the style corresponding the the "select" render intent.
        </p>
    </div>
  </body>
</html>
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补充：企业软件 ,  地理信息系统