Nook reader problems with epub file generated with docbook-xsl-ns-1.76.1

Hello, 

I created an epub file with docbook-xsl-ns-1.76.1 which works on all readers
tested - except on the Nook (or actually with the NOOK for PC software). I
stripped the epub file to make it as simple as possible. I can load and open
the book now (opening didn't work before - but only one problem at a time
:). There is something wrong though when I look at the book in the library
in NOOK for PC: It doesn't show the title (should be "Book title") and
author (should be "Firstname Lastname"). It shows the filename
"nooktest.epub" and "Unknown Author" instead. The Nook software seems to
fail to read <dc:title> and <dc:creator>. Why I don't know. I've attached
the very simple epub file - maybe someone has an idea what's wrong?
(Epubcheck 1.2 says the file is OK. No problem with Adobe Digital Editions
either.) 

Boris