Maybe Visual Studio hadn't picked up the changes in the Markup yet? When you run into issue like this, try compiling the site using Build | Build Web Site or Build SOlution.
The reason I asked for more code is the fact that the control you're targeting is defined in the markup. If you gave it a different name,such us lstThemes, it explains why IntelliSense couldn't find it.
Where might I do that? I need to get a data item in code behind from a listview
Best place is in one of the general, non-book specific forums here: http://p2p.wrox.com/asp-net-4-539/