NetStream.publish() to AMS ends up with 1kb file.

I'm using Adobe Media Server 4.5 and the FLEX 4.6.0 sdk.

I have an .swf application that connects to Adobe Media Server over RMTP, takes audio and video input from the user's webcam and mic, and does a NetStream.publish() to stream the file to the server. When the user is done, I do a NetStream.stop(). On occasion, the resulting file will end up with a size of 1kb.

What's causing this and how can I prevent it, or otherwise end the session and inform the user that something went wrong?

Alternatively, these forums seem dead, so does anyone know of a place where my question might be better suited?