epub3 missing Navigation Document?

Hi,
I am experimenting with the epub3/html5 latest xsl (build 9230) on
DB5.0 files and I get invalid epubs (validated against the latest
epubcheck-3.0b3).

Apparently the epubs are missing the navigation document along with
the relevant reference to it in the opt manifest.

Do I have to file a bug or I am missing something?

Thanks,

__peppo