Vorbis - Feb 2005 - Pretec Allegro, can it really play Oggs?

I have bought a Pretec Allegro. Placing some of my mp3's and Oggs on the
"iDisk-tiny" and plugging it into the Allegro allows me to play the 
mp3's, but _the Oggs don't work_!

What am I missing? It is advertised on the website, on the box, in the 
manual... Anyone else tried an Allegro?

Hugo