I've passed the test, and been able to type in chatter, but it doesn't seem like anyone can see my messages, yet I see theirs. Also my username is in purple while everyone else's is in green. I'm curious if this is a newbie thing, or if there's something else I must do.
I rarely use chatter, but the length could be an issue [quick 1-2 sentences] regarding name colour, it could just be a way to find your post quicker. When I have used my coven chat I've noticed the colour is different for a high priest/priestess, council members and regular members. [mods and admin would also have a different colour I think]
The purplecolourjust signifies that YOU typed that message, and everyone else's messages appear green.
As for not getting seen... I'm not sure...
> check your internet connection
> make sure you don't have more than one chatter open
> make sure it doesn't contain text speak
> make sure it isn't too long
> your message might've been missed if the chat was busy