Adding book from command line

I seem to be missing some... running in Linux, 0.8.36 version.

Run

calibredb add book.epub

The file appears in the GUI, the directory is populated with a file (cover, epub and metadata), the metadata is all populated right, but if I try to open the file in the GUI, it says "no available formats".

If I take the very same epub file and add it from the GUI, it's all happy.

Am I missing the obvious (most probably).

If anybody has an idea to try, let me know.

Thanks!

Bruce