_The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

I have a user control containing the following mark-up :

<%@ Control Language="C#" AutoEventWireup="false" CodeFile="tab.ascx.cs" Inherits="tab" %>
<asp:Literal ID="ltl_Tabs" runat="server"></asp:Literal>
<asp:PlaceHolder ID="ph_Content" runat="server">
</asp:PlaceHolder>

I have also a child user control which uses the above user control in it with the following markup :



        
<%@ Control Language="C#" AutoEventWireup="false" CodeFile="city_tabs.ascx.cs" Inherits="Pages_City_Tab_city_tabs" %>



<%@ Register TagName="Tab" TagPrefix="Tab" Src="../../UserControls/tab.ascx" %>

<Tab:Tab NumberOfTabs="3" TabsUrl="#,#,#" TabsText="a,b,c" Sel ...