.net webfrom 前端使用ajax post方法向后端传值一直进入error 报 401 (Unauthorized)错

这次寒假有一个asp.net课设，题目是在线购物系统，所以想着做一个仿造小米商城，其中需要用到前端向后端传值。我用的ajax post，但是一直进入error 报Failed to load resource: the server responded with a status of 401 (Unauthorized)错

public static string Getit(string device)
        {
            return "qqq";   
            if (HttpContext.Current.Session["username"] != null)
            {
                return "您还未登陆" + device;
            }
            else
            {
                MyDb myDb = new MyDb();

                string sql = "INSERT INTO [dbo].[Order] VALUES ("+(DateTime.Now-new DateTime(1970,1,1,0,0,0)).ToString()+" "+ HttpContext.Current.Session["username"]+" "+ HttpContext.Current.Session["name"]+" "+device+" "+DateTime.Now.ToString()+" 0 0)";
                

                SqlParameter[] pas = { };
                myDb.querry(sql);

                return "购买成功";
            }
            
        }

<script>
                $(function () {
                    $("td input").click(function () {
                        var device = $(this).parent("div").siblings("div").children("marquee").text();
                        //alert(name);

                        $.ajax({

                            type: "post",
                            url: '小米商城.aspx/Getit',
                            
                            contentType: "application/json; charset=utf-8",
                            data: "{device:'" + device + "'}",
                            data:'json',
                            success: function (result) {
                                alert(result + "成功");
                            },
                            error: function (result) {
                                alert(result + "失败");
                            }


                        });
                    });
                })
            </script>