A simple way to manage archive pages for your Custom Post Types.
They're probably not public, or do not have an archive page.
Custom Post Types are not "a new thing" anymore, their support in themes and plugins is much better now. That is why I consider the previous options obsolete, and removed them.
Eventually, check out my blog for more infos or tips (sorry guys, it's in French, but feel free to leave a comment in English).