net ，js脚本调用后台方法不接收返回值

js脚本： 

window.onload = (function () {
            //此处参数名要注意和后台方法参数名要一致
            // var params = '{tjd:"' + identity_ + "',lon:'" + listlon + "',lat:'" + listlat + '"}';
            $.ajax({
                type: "POST",                   //提交方式
                url: "scoreManage.aspx?Method=ShowMapInfo",   //提交的页面/方法名
                beforeSend: function (XMLHttpRequest) {
                    //$('#tipsDiv').text("正在查询...");
                },
                success: function (data) {
                alert("success");
                },
                error: function (xhr, msg, e) {
                    alert(XMLHttpRequest.responseText);
                }
            });
        }); 

page_Load

 if (Request["Method"]!=null)
                {

//接收参数，即要方法的方法名称
                    string method = Request.QueryString["Method"];
                    Type tp = this.GetType();
                    MethodInfo methodInfo = tp.GetMethod(method);
                    methodInfo.Invoke(this, null);
                }

//调用方法

 public Dictionary<string, object> ShowMapInfo()
        {
            Dictionary<string, object> dict = new Dictionary<string, object>();
            return dict;

        }

js调用后台并接收返回值

  window.onload = (function () {
        //此处参数名要注意和后台方法参数名要一致
        // var params = '{tjd:"' + identity_ + "',lon:'" + listlon + "',lat:'" + listlat + '"}';
        $.ajax({
            type: "POST",                   //提交方式
            url: "RuleDetail.aspx/ShowInfo",   //提交的页面/方法名
            data: null,                   //参数（如果没有参数：null）
            dataType: "json",               //类型
            contentType: "application/json; charset=utf-8",
            beforeSend: function (XMLHttpRequest) {
                //$('#tipsDiv').text("正在查询...");
            },
            success: function (data) {
                fake = data.d.dataArr;
                renderTable(fake);
            },
            error: function (xhr, msg, e) {
                alert(XMLHttpRequest.responseText);
            }
        });
    });

后台方法

 /// <summary>
        /// 质量信息考核标准
        /// </summary>
        /// <returns></returns>
        [System.Web.Services.WebMethod]
        public static Dictionary<string, object> ShowInfo()
        {
            Dictionary<string, object> dict = new Dictionary<string, object>(); 
            dict.Add("result", "success");
            return dict;
        }