ajax 自动完成扩展器不起作用

我在文本框中有一个自动完成扩展器，它将记录显示为数据库中的列表，但是当我单击文本框并开始输入任何内容时，却没有发生任何事情。我的html代码是

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <asp:AutoCompleteExtender ID="TextBox1_AutoCompleteExtender" runat="server" 
         Enabled="True"  TargetControlID="TextBox1" ServicePath="~/WebService.asmx" 
                ServiceMethod="GetCompletionList"
                MinimumPrefixLength="2" 
                CompletionInterval="1000"
                EnableCaching="true"
                CompletionSetCount="20"
                DelimiterCharacters=";, :"
                ShowOnlyCurrentWordInCompletionListItem="true" >
    </asp:AutoCompleteExtender>

我的网络服务是

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web;
    using System.Web.Services;
    using System.Data;
    using MySql.Data.MySqlClient;
    using System.Configuration;

     /// <summary>
     /// Summary description for WebService
    /// </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 WebService : System.Web.Services.WebService {

    public WebService () {

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

    [WebMethod]
    public static List<string> GetCompletionList(string prefixText, int count)
    {
        MySqlConnection con = new MySqlConnection(ConfigurationManager.AppSettings["cn"]);
        if (con.State == ConnectionState.Closed)
            con.Open();
        MySqlCommand cmd = new MySqlCommand("SELECT gotra FROM tbgotra WHERE gotra LIKE '%" + prefixText + "%'",con);
        List<string> k = new List<string>();
        using (MySqlDataReader sdr = cmd.ExecuteReader())
        {
            while (sdr.Read())
            {
                k.Add(sdr["gotra"].ToString());
            }
        }
        con.Close();
        return k;
    }
   }

尝试添加这一行，我记得我曾经遇到过同样的问题，它在本地适用于我，但不适用于实时。

[WebMethod]
[System.Web.Script.Services.ScriptMethod] <-- Add this line
public static List<string> GetCompletionList(string prefixText, int count)
....