Can't Stream Audio Other Than Through Mic

[DucksUnlimited]

I try to play music off of Procaster, and the only thing that ever comes through the stream is whatever my Built-In mic picks up. That's not good.

Reading through the other threads, most people say to select "Speaker's Audio" as your output, but I don't even HAVE that as a choice. Uninstalling/reinstalling did nothing, and I've never gotten this to work properly every time I've tried to run it. What's up, Livestream?