jquery兼容性问题

<html>   
<head>   
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<title>jquery xml解析</title>   
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript">   
    $(document).ready(   
            function() {   
                $.ajax( {   
                    url : "xx.xml",
dataType: "xml",
                    success : function(xml) {   
//alert(xml);
                        $(xml).find("province").each(function() {   
                            var t = $(this).attr("name");//this->      
                                $("#DropProvince").append(   
                                        "<option>" + t + "</option>");   
                            });   
                    }   
                });   
                $("#DropProvince").change(   
                        function() {   
                            $("#sCity>option").remove();   
                            var pname = $("#DropProvince").val();   
                            $.ajax( {   
                                url : "xx.xml", 
dataType :"xml",
                                success : function(xml) {   
                                    $(xml).find(   
                                            "province[name='" + pname   
                                                    + "']>city").each(   
                                            function() {   
                                                $("#sCity").append(   
                                                        "<option>"  
                                                                + $(this)   
                                                                        .text()   
                                                                + "</option>");   
                                            });   
                                }   
                            });   
                        });   
            });   
</script>   
</head>   
<body>   
<form id="form1">   
<div>   
    <select id="DropProvince" style="width: 60px;">   
        <option>请选择</option>   
    </select>   
    <select id="sCity" style="width: 60px;">   
    </select>   
</div>   
</form>   
</body>   
</html>  xx.xml:
<?xml version="1.0" encoding="utf-8" ?>     
<provinces>     
    <province name="湖北">     
        <city>武汉</city>     
        <city>黄石</city>     
        <city>宜昌</city>     
        <city>天门</city>     
    </province>     
    <province name="湖南">     
        <city>邵阳</city>     
        <city>长沙</city>     
        <city>岳阳</city>     
    </province>     
    <province name="广东">     
        <city>广州</city>     
        <city>深圳</city>     
    </province>     
</provinces>  这个代码在火狐下正常读取，但是在IE6下却没有任何反映，望高手指教，非常感谢！