using c# to programmatically add custom Web User Controls

Hi,
I'm trying to add a web user control I made to an asp:Panel on my web page.
I think all my references and registers are correct:
<%@ Register src="~/web_user_controls/PostWUC.ascx" tagname="PostWUC" tagprefix="uc1"%>
<%@ Reference Control="~/web_user_controls/PostWUC.ascx" %>
because if I try to add it manually to the page using <uc1:PostWUC ...> I get no errors.
But I only know the number of PostWUCs on one page at runtime, so I would need to add
them using a for loop.
My problem now is that I can't find PostWUC in the list that drops down (in Visual Studio 2008),
and when I manually enter "PostWUC p = (PostWUC)control;" (control has been made using loadControl="...")
I receive an error that the type or namespace can't be found.
How can I solve this?
Thanks in advance,
Serris

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