อยากจะทำ auto complete แต่เรียกแล้วมันไม่ไปที่ Webservice.asmx คือแก้ยังไงหรอ

                                                    <asp:TextBox ID="txtFirstNameEN" MaxLength="500" runat="server" Width="192px" />

                                                    <ajaxToolkit:AutoCompleteExtender runat="server" ID="AutoCompleteExtender1" 
                                                        TargetControlID="txtFirstNameEN" 
                                                        ServiceMethod="GetCompletionList" ServicePath="WebService.asmx" 
                                                        MinimumPrefixLength="2" 
                                                        ShowOnlyCurrentWordInCompletionListItem="true">  
                                                    </ajaxToolkit:AutoCompleteExtender>  

//ส่วนหน้าบ้าน

<%@ WebService Language="C#" CodeBehind="~/App_Code/WebService1.cs" Class="WebService1" %>

//ส่วนหลังบ้าน

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;

/// <summary>
/// Summary description for WebService1
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
// 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 WebService1 : System.Web.Services.WebService {

    public WebService1 () {

        //Uncomment the following line if using designed components 
        //InitializeComponent(); 
    }

    [WebMethod]
    public string HelloWorld() {
        return "Hello World";
    }

    [WebMethod]
    [System.Web.Script.Services.ScriptMethod]
    public static string[] GetCompletionList(string prefixText, int count)
    {
        return new string[] { "test1", "test2", "test3" };
    }
    
}