How can use autocompleteextender of ajax control toolkit using web service.

Question

my aspx page is auto.aspx

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>

<form id="form1" runat="server">

            <cc1:ToolkitScriptManager ID="ToolkitScriptManager1" EnablePageMethods="true" runat="server">

           

        </cc1:ToolkitScriptManager>

        <div>

<asp:TextBox ID="txtcon" runat="server"></asp:TextBox>

            <cc1:AutoCompleteExtender ID="txtcon_AutoCompleteExtender" runat="server" 

                TargetControlID="txtcon"

                ServicePath="Countries.asmx" 

                ServiceMethod="GetCompletionList"

                MinimumPrefixLength="1"

                CompletionInterval="1000"

                EnableCaching="true"

                CompletionSetCount="20"

                >

            </cc1:AutoCompleteExtender>

    </div>

    </form>

and 

web service is Countries.asmx is

using System;

using System.Collections;

using System.ComponentModel;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Services;

using System.Web.Services.Protocols;

using System.Xml.Linq;

using AjaxControlToolkit;

using System.Data.SqlClient;

using System.Configuration;

using System.Collections.Generic;

using System.Collections.Specialized;

namespace AutocompleteExample

{

    /// <summary>

    /// Summary description for Countries

    /// </summary>

[WebService(Namespace = "http://tempuri.org/")]

    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

    [ToolboxItem(false)]

    // To allow this Web Service to be called from script, using ASP.NET AJAX,          //uncomment the following line. 

     [System.Web.Script.Services.ScriptService]

    public class Countries : System.Web.Services.WebService

    {

   [WebMethod]

        [System.Web.Script.Services.ScriptMethod]

        public string[] GetCompletionList(string prefixTest,int count)

        {

            string connStr = ConfigurationManager.ConnectionStrings["san"].ConnectionString;

            SqlDataAdapter cmd1 = new SqlDataAdapter("select * from tbl_country where country_name like '" + prefixTest + "%'", connStr);

            DataSet ds2 = new DataSet();

            cmd1.Fill(ds2, "countries");

            DataTable dt1 = ds2.Tables["countries"];

            List<string> country = new List<string>(10);

   

            foreach (DataRow dr in dt1.Rows)

            {

                country.Add(dr["country_name"].ToString());

                

            }

            return country.ToArray();

        }

    }

It is not show any error but web service individual method run but it can not call by .aspx page  Textbox when press any char

please solve my problems

Thanx