[O] cannot export to openoffice

[Luca Ferrari]

Hi all,
I'm running emacs 24.3.1 on Linux, and I've LibreOffice installed.
When trying to export an org buffer (C-c C-e) I don't have any
OpenDocument option.
I've checked and I've the "zip" command on my path. What else should I check?

Thanks,
Luca