iTunes Server and audiobooks?

Hello, I have a RNDP4000 running OS version 6.7.4. I've set up a share and enabled the iTunes server on it. From my local Mac controlling the iTunes library, I've set the iTuned Media folder location to that share, so all of my media is located on the NAS. This works great for music. I added all my albums and fair enough, I can access them from any computer inside my local network, all fine.

However, my audiobooks don't show up. On the Mac controlling the library I added them as audiobooks, and they show up fine (With show up, I'm talking about the Mac's local library with the media location being the NAS share), however, when I try to access the library from another machine, I can only see all the music, but no audiobooks (It says 'There are no audioboks on NAS'). 

If I look into the share directly, the audiobooks get saved alongside the music, so for example I have a folder called AC_DC or Kiss for my music, but also in the same folder I have folders called Stieg Larsson or David Lagercrantz, so they do indeed get saved on the NAS, why can't I access them?

Thanks in advance!