Newbie question: Composite Control in VS 2005

[Guest]

I'm going through "ASP.NET 2.0 Step By Step" reproducing the examples in VS
2005 using C#. I'm new to both VS 2005 and ASP.NET, but I'm very familiar
with C#, VS 2003 and Windows Forms programming.

I build a custom Rendered control (derived from WebControl), it appears in
the Toolbox, and I use it. Then in the same project, I build a custom
Composite control (derived from CompositeControl). The book becomes confused
here, because I think they accidently swapped text from a later example.
Anyway, the new control doesn't appear in the Toolbox. If I do Choose Toolbox
Items, the new control exists and is checked. If I do a Show All in the
Toolbox I can see the control grayed out with a different icon, but I can't
select it. I can add the control to the page by editing the page source
directly, and it works.

I can load the entire sample code project from the companion CD, and in that
project, the Control appears in the Toolbox as a normal control. I've
compared my project to the sample project and can't see what's different. Can
anyone give me a hint?