WCF / ASMX :: AutoComplete Extender Not Calling Web Service

I am using AutoComplete ASP.NET AJAX Control toolkit AutoCompleteExtender control When I am using my web service as Service Path, its not working.my web services code below

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Data.SqlClient;
using System.Data;
using System.Web.Script.Services;
namespace OnlineSalesGrid
{
/// <summary>
/// Summary description for sample
/// </summary>
[WebService(Namespace = [URL]]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.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 sample : System.Web.Services.WebService
{
[WebMethod]
public static string[] GetCompletionList(string prefixText, int count)
{
List<string> returnData = new List<string>();
SqlConnection con = new SqlConnection("Data Source=CARPATHIA\SQLEXPRESS;Initial Catalog=OnlinesaleGrid;Persist Security Info=True;User ID=sa;Password=c0rpusdata");
string sql = "select Customer_Name from Customer_Master where Customer_Name like '%" + prefixText + "%'";
SqlCommand cmd = new SqlCommand(sql, con);
con.Open();
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
while (reader.Read()) { returnData.Add(reader["Customer_Name"].ToString()); }
return returnData.ToArray();
}
[WebMethod]
public static string[] GetCompletionList1(string prefixText, int count)
{
List<string> returnData = new List<string>();
SqlConnection con = new SqlConnection("Data Source=CARPATHIA\SQLEXPRESS;Initial Catalog=OnlinesaleGrid;Persist Security Info=True;User ID=sa;Password=c0rpusdata");
string sql = "select Customer_Code,Customer_Name from Customer_Master where Customer_Code like '%" + prefixText + "%'";
SqlCommand cmd = new SqlCommand(sql, con);
con.Open();
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
while (reader.Read())
{
returnData.Add(reader["Customer_Code"].ToString());
}
return returnData.ToArray();
}
}
}

Html Code is

<asp:ScriptManager ID="toolscpt1" runat="server" >
<Services>
<asp:ServiceReference Path="~/sample.asmx" />
</Services>
</asp:ScriptManager>
<asp:TextBox
ID="txtcname" runat="server" CssClass="textbox" onBlur='funblurcolor(this.id)' onFocus='funfocuscolor(this.id)'
ontextchanged="txtcname_TextChanged1" onkeypress="javascript:if(window.event.keyCode == 13) document.getElementById('txtphno').focus" ></asp:TextBox>
<asp:AutoCompleteExtender ID="txtname_AutoCompleteExtender"
runat="server" Enabled="True" ServiceMethod ="GetCompletionList" ServicePath="~/sample.asmx"
MinimumPrefixLength="1" CompletionSetCount ="12" EnableCaching ="true" CompletionInterval ="500"
TargetControlID="txtcname" ></asp:AutoCompleteExtender>