ดูโค้ดให้ผมหน่อยครับ AutoCompleteextender ไม่ทำงานอะครับ

public DataTable GetRecords(string prefixText)
        {
            string strConn = ConfigurationManager.ConnectionStrings
            ["ManageMentConnectionString"].ConnectionString;
            SqlConnection con = new SqlConnection(strConn);
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = con;
            cmd.CommandType = System.Data.CommandType.Text;
            cmd.Parameters.AddWithValue("@name", prefixText);
            cmd.CommandText =
            "select dbo.Professor.name from dbo.Professor where dbo.Professor.name like '%'+@name+'%'";
            DataSet objDs = new DataSet();
            SqlDataAdapter dAdapter = new SqlDataAdapter();
            dAdapter.SelectCommand = cmd;
            con.Open();
            dAdapter.Fill(objDs);
            con.Close();
            return objDs.Tables[0];
        }

<asp:TextBox ID="txtHelp2" runat="server" Width="200px"></asp:TextBox>
                <ajaxToolkit:AutoCompleteExtender ID="txtHelp2_AutoCompleteExtender" 
                    runat="server" CompletionInterval="500" DelimiterCharacters="" Enabled="True" 
                    MinimumPrefixLength="1" ServiceMethod="GetRecords" 
                    ServicePath="~/WebService1.asmx" TargetControlID="txtHelp2">
</ajaxToolkit:AutoCompleteExtender>