Facetime Audio not working

Just upgraded to 10.9.2 and now I have Facetime Audio. Hooray! Thing is, it's not working. I am trying to use it on two iMacs in the same house, on the same network. We can text chat between us and we can use Facetime video just fine, but when I call the other Mac using Facetime Audio, it rings at my end, but nothing on the other iMac. If the other iMac rings me with audio, it rings on my imac and my iphone, but when I answer we cannot hear each other at all. I can see the audio meter going, but not sound is heard. Otherwise, system sound and mic is working fine.

So very bizarre behaviour with Facetime Audio. Is it just not ready for prime time, or is there an answer to this issue?