Problem with Dreambox audio

[Oordo2]

Hello Everybody
I have this strange situation with VLC 0.86h and Dreambox 7020si:
- when playing a DVD all is ok on both PC and Dreambox
- copying all DVD folders to the PC and then playing from them, results are ok
only on the PC, on the Dreambox is ok only for the video, the audio is silent.
Adjusting the volume has no effect and actually I don't understand why this should
Improve given that when playing directly from the DVD all is ok.
What could be different in this two situations?
Thanks
Albert O.