DropDownList with OptionGroup

<%@ Page Language="C#" AutoEventWireup="true" Codebehind="UseWithObjectDataSource.aspx.cs"
    Inherits="TestWebApplication.UseWithObjectDataSource" MasterPageFile="~/Site1.Master"
    Title="UseWithObjectDataSource" %>

<%@ Register TagPrefix="ddlb" Assembly="OptionDropDownList" Namespace="OptionDropDownList" %>

<asp:Content ID="Content1" ContentPlaceHolderID="MainContent" runat="Server">
    <div>
        Choose food:
        <ddlb:optiongroupselect id="ogsFinishedProduct" runat="server" appenddatabounditems="True"
            autopostback="True" datatextfield="food" datavaluefield="id">
                <ddlb:OptionGroupItem ID="OptionGroupItem1" runat="server" Value="-1" Text="-- Select --" Selected="True" />
            </ddlb:optiongroupselect>
        <br />
        <br />
        <asp:GridView ID="GridView1" runat="server" DataSourceID="ObjectDataSource1" />
    </div>
    <asp:ObjectDataSource ID="ObjectDataSource1" runat="server" OldValuesParameterFormatString="original_{0}"
        SelectMethod="GetByFinishedProduct" TypeName="TestWebApplication.DataClassForObjectDataSource">
        <SelectParameters>
            <asp:ControlParameter ControlID="ogsFinishedProduct" Name="id" PropertyName="SelectedValue"
                Type="Int32" />
        </SelectParameters>
    </asp:ObjectDataSource>
</asp:Content>