After making a fresh install of Ubuntu Server 12.04 64 bit on an Asus 1215 and Asus 1005 laptop (same results in both machines), I am only able to activate streaming. When the hardware audio output (ALSA) is selected, neither the onboard sound or the streaming work.
Also, when the onboard audio sound is selected, the LIQUIDSOAP_PROCESS_ID = FAILED when I run sudo airtime-check-system.
However, when the hardware audio output is deselected, then LIQUIDSOAP_PROCESS_ID = 11620, and the streaming works fine.
The Asus 1005 used to work with Ubuntu 10.04, and the Asus 1215 with Ubuntu 11.10 (needed the newer version for support of the newer sound device in this laptop).