I'm new to DD and I really like it

Unfortunately I have a small problem with AC3 all channels, and especialy with NRJ 12 HQ on 13°E (11585 V).
I'm using Ffdshow as audio codec, it works great with other DVB apps (i.e. Skyview). It works nice with DD too, but I if I select an AC3 audio Pid then I don't get no audio at all. Also, the Ffdshow icon don't show. All channels with AC3 are the same, but with NRJ 12 HQ if I select the AC3 audio Pid, then it goes back to normal Pid.
I tried with Nvidia and Cyberlink codecs, and I get the same result, so I don't think it's a codec problem.
My DVB card is a Skystar 2 and my sound card is a Sound Blaster Live.
Help would be appreciated.
Thanks for this great software !