auto complete extender did not work in asp.net 4.5

Hi,

Please, can anyone give me idea or help me out why my auto complete extender is not working.

Thanks in advanced.

Here is my Frontend and ASMX

 <ajax:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server"></ajax:ToolkitScriptManager>

 <asp:TextBox ID="txtIng1" runat="server" CssClass="ddlbranch textboxradiuscolor" Width="250" Height="20"></asp:TextBox>  

 <ajax:AutoCompleteExtender ID="AutoCompleteExtender2" runat="server" TargetControlID="txtIng1"
                                                                MinimumPrefixLength="1" ServiceMethod="getProductList"
                                                                CompletionInterval="1000" ServicePath="~/WebServices/InvProduct.asmx"
                                                                CompletionSetCount="20" DelimiterCharacters=";, :"
                                                                ShowOnlyCurrentWordInCompletionListItem="true"
                                                                OnClientItemSelected="OnContactSelected"
                                                                CompletionListCssClass="completionlist" CompletionListHighlightedItemCssClass="completionlisthighlight"
                                                                CompletionListItemCssClass="completionlistitem">
 </ajax:AutoCompleteExtender>

using System;
using System.Collections;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Xml.Linq;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;


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

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

        [WebMethod(EnableSession = true)]
        public string[] getProductList(string prefixText, int count)
        {
            string status = Session["status"].ToString();
            string constatus = Session["conStatus"].ToString();
            SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings[constatus]);

            //ADO.Net         
            DataSet ds = new DataSet();
            DataTable dt = new DataTable();

            //     con.ConnectionString = strCn;
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = con;
            cmd.CommandType = CommandType.Text;

            //prevent SQL injection--------//
            cmd.CommandText = "select * from Inv_Product Join Branch b on b.BranchId= Inv_Product.BranchId Where InvProductName like @myParameter and Inv_Product.DeleteStatus = 'N' and b.DeleteStatus = 'N'";
            cmd.Parameters.AddWithValue("@myParameter", "%" + prefixText + "%");

            try
            {
                con.Open();
                cmd.ExecuteNonQuery();
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(ds);
            }
            catch
            {
            }
            finally
            {
                con.Close();
            }
            dt = ds.Tables[0];

            //Then return List of string(txtItems) as result
            List<string> txtItems = new List<string>();
            String dbValues;

            foreach (DataRow row in dt.Rows)
            {
                //String From DataBase(dbValues)
                dbValues = row["InvProductName"].ToString();
                dbValues = dbValues.ToLower();
                txtItems.Add(dbValues);
            }

            return txtItems.ToArray();
        }
    }
}