how to refresh particular div using web service?

Question

 i am using below code to refresh particular div with time interval

 but it's not working

<script type="text/javascript">

        $(document).ready(

            function () {

                setInterval(function () {

                    ShowCurrentTime();

                }, 3000);

            });

        function ShowCurrentTime() {

            $.ajax({

                type: "POST",

                url: "ARcalls.aspx/Getcount",             // webmethod

                data: '{UserId : "' + $("#<%=Label2.ClientID%>")[0].value + '"}',     // paramater pass to webmethod from masterpage

                contentType: "application/json; charset=utf-8",

                dataType: "json",

                success: OnSuccess,

                failure: function (response) {

                   alert(response.d);

                }

            });

        }

        function OnSuccess(response) {

            $('#show').text('I am getting refreshed');

        }

ARcall.aspx.cs

ARCall.aspx/Getcount

 [System.Web.Script.Services.ScriptMethod()]

    [System.Web.Services.WebMethod]

 public string Getcount(string UserID)

    {

        //UserID = Convert.ToString(Session["UserId"]).ToString();

        SqlConnection cn =

            new SqlConnection(ConfigurationSettings.AppSettings["CnnStr"]);

        SqlCommand cmd = new SqlCommand("SELECT count([id]) FROM [AR] WHERE ([UserID] = @UserID and outcome in ('Asked to Call back','Not reachable','Not recieved'))", cn);

        cmd.Parameters.Add("UserID", UserID);

        String unitsInStock = "";

        cn.Open();

        using (SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))

        {

            while (dr.Read())

                unitsInStock = dr[0].ToString();

        }

        //System.Threading.Thread.Sleep(3000);

        return unitsInStock;

    }