Retrieve Dynamically Created Controls

I am building a webform dynamically but when I go to get the values the placeholder has no controls.  Every control added has an unique ID.  Does anyone know what I am doing wrong (language is C#).   
 
aspx page
<asp:UpdatePanel ID="upShoppingCart" runat="server" UpdateMode="Conditional" >
                    <ContentTemplate>
                        <asp:PlaceHolder ID="phShoppingCart" runat="server" />
                        <br /><asp:Button ID="btnUpdateCart" runat="server" Text=& ...