Hmm... the only reason that should happen is if the channel ID you're using doesn't match the account you authenticated with in the browser. (That is, if you're logged in with a different account than the one the ID is attached to.) I'd suggest double-checking your channel ID and then if that still doesn't fix it, you're welcome to turn Debug Logging on and then send me the text file it generates via Twitter DM. (The log generates in the Twitch Item Flood_Data folder.)
I'd suggest turning it on, then restarting the program, and trying to authenticate again so it gets the full steps logged.