Speaker's Audio will not work

[CeeDeeCaffeine]

Hi,
I have Livestream Procaster 20.3.0M on my MacBook Pro (OS X 10.6.8) and recently I've encountered a problem with the audio streaming. I would like to stream the audio that comes from my computer's speakers whenever I'm working (I used to have iTunes open while broadcasting but this affected the streaming quality), but whenever I select Speaker's Audio on the mixer, absolutely no sound is detected.
Is there any way to fix this?