Adding a document management center site is odd. Once added there is a link in the top navigation, which if clicked brings up the standard page giving you the Upload a Document button. Question: If a user clicks on the link taking them to this page, how is one meant to get to the list of documents?
If you do head over to the Libraries link in the left side menu, you do get a reference to a document library, which I'm hoping is associated with the Document Management Center. Question: When you add a Document Management Center site, is that actually the Document Library I'm seeing under Libraries?