引用detailview内部控件？

如何在代码页引用PopupControlExtender1 和Calendar1 控件？
<asp:DetailsView ID="DetailsView2" runat="server" AutoGenerateRows="False" BackColor="LightGoldenrodYellow"
                    BorderColor="Tan" BorderWidth="1px" CellPadding="2" DataKeyNames="username" DataSourceID="SqlDataSource1"
                    ForeColor="Black" GridLines="None" Height="50px" Width="621px">
                    
                    <Fields>
                        <asp:TemplateField>
                                                            
                            <EditItemTemplate>                                                                
                                            <asp:TextBox ID="birthdayTextBox" runat="server" Text='<%# Bind("birthday") %>'></asp:TextBox>
                                            <ajax:PopupControlExtender ID="PopupControlExtender1" runat="server" 
                                            TargetControlID="birthdayTextBox" PopupControlID="Panel1">
                                            </ajax:PopupControlExtender>                                            
                                            <asp:Panel ID="Panel1" runat="server" Height="50px" Width="125px">
                                                <asp:UpdatePanel id="UpdatePanel1" runat="server">
                                                    <contenttemplate>
<asp:Calendar id="Calendar1" runat="server" OnSelectionChanged="Calendar1_SelectionChanged"></asp:Calendar> 
</contenttemplate>
                                                </asp:UpdatePanel>
                                            </asp:Panel>
                                        
                            </EditItemTemplate>
                        </asp:TemplateField>
                    </Fields>                </asp:DetailsView>