微信公众号读取微信用户经纬度为空为什么读取不出来急急，请高手帮我看一下。

 <script src="http://res.wx.qq.com/open/js/jweixin-1.0.0.js" type="text/javascript"></script>        <script >            wx.config({
                debug: false,
                appId: '<%=appId%>',
                timestamp: '<%=timestamp%>',
                nonceStr: '<%=nonceStr%>',
                signature: '<%=signature%>',
                jsApiList: ['checkJsApi', 'getLocation']
            });
           
           
            wx.ready(function () {                wx.checkJsApi({
                    jsApiList: ['getLocation'], // 需要检测的JS接口列表，所有JS接口列表见附录2,  
                    success: function (res) {
                        var latitude;
                        var longitude;
                        var speed;
                        var accuracy;
                        var geocoder = null;
                        wx.getLocation({
                            type: 'gcj02',
                            success: function (res) {
                                latitude = res.latitude; // 纬度，浮点数，范围为90 ~ -90    
                                longitude = res.longitude; // 经度，浮点数，范围为180 ~ -180。    
                                speed = res.speed; // 速度，以米/每秒计    
                                accuracy = res.accuracy; // 位置精度  
                                
                                document.getElementById("jindu").innerHTML = latitude;
                                document.getElementById("weidu").value = latitude;                            },
                            cancel: function (res) {
                                alert('未能获取地理位置');
                            }
                        });
                    }
                });                
               
            });  </script>
        
       <input type="text" id="jindu" runat="server" style="width: 1px" />  <input type="text" id="weidu" runat="server" style="width: 1px" />页面显示出来为空没有读取经纬度
    </div>