[Evolution] Evolution and sounds

[Sabbia <sabbia libero it>]

Hi, this is the first message for me.
I have Evolution 1.2 on Mandrake 9 but I can't hear any sound: it
happens on calendar (when I set "Play a sound X minutes before task")
and when I set "Play a sound when new mail arrives".

I have tried with .OGG and .WAV files.

Does Evolution use an external software to play sounds?
What can I do?

Thank you very much and sorry for my poor English

Sabbia