[Zope] commenting the Zope Book at the new site: broken?

Hi, I just looked at http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/AppendixA.stx to see whether or not I would find there a <dtml-tree header...> example (which I didn't :-| ). I see the comments, and I'm logged in, but I can't add a comment myself. Why? Is there something broken? Tia, Tobias