unable to access web services in auto complete extender

See more:

ASP.NET

webservice

my code is AT AutoComplete.aspx page,

<asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
    <services>
        <asp:ServiceReference Path="~/AutoComplete.asmx" />
    </services>
    <asp:TextBox ID="TxtCompName" Width="350px" runat="server" AutoPostBack="True" 
        ontextchanged="TxtCompName_TextChanged"/>

    <asp:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server"
        CompletionListHighlightedItemCssClass="autocomplete_highlightedListItem" CompletionListItemCssClass="autocomplete_listItem"        
        CompletionListCssClass="autocomplete_completionListElement" 
        Enabled="True" ServiceMethod="GetCompletionList" 
        ServicePath="~/AutoComplete.asmx" TargetControlID="TxtCompName" UseContextKey="True" 
        CompletionInterval="100" DelimiterCharacters="" CompletionSetCount="20" MinimumPrefixLength="1" />

the web services file is present in my projet:(AutoComplete.asmx) and Web servics Code Behind(AutoComplete.cs) is in app_code folder.
The code is:

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService]
public class AutoComplete : System.Web.Services.WebService
{
    public AutoComplete()
    {
        //Uncomment the following line if using designed components 
        //InitializeComponent(); 
    }

    [WebMethod]
    public static string[] GetCompletionList(string prefixText, string contextKey)
    {
        SqlConnection conn;
        SqlCommand cmd;
        string cmdString = "SELECT comp_name FROM tbl_admin_Brand WHERE comp_name LIKE'" + prefixText + "%'";

        conn = new SqlConnection("Data Source=INDIA\\SQLEXPRESS;Initial Catalog=BrandMutual;User ID=sa1;Password=123");
        cmd = new SqlCommand(cmdString, conn);
        conn.Open();
        SqlDataReader myReader;
        List<string> returnData = new List<string>();
        myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
        while (myReader.Read())
        {
            returnData.Add(myReader["comp_name"].ToString());
        }
        return returnData.ToArray();
    }
}

But my problem is I unable to access Webservices,so my auto extendor give nothing,

And if i put web services code at AutoComplete.cs page then it work fine,
So what can i do.