Quote:
What could possibly be going wrong?

I think the problem is the "on Join" bit.

I've never seen anyone else's name but that of my bot in the users list.
Try a small test code to at least make sure the whispers work, such as
Code:
on *:TEXT:!test:#: {
  msg $chan /w $nick This is an automated bounceback. Thanks for checking with me!
}

I think this is what you might be having trouble with, but as you can see, I'm not even one year old in mIRC. I'm just relaying the troubles I've had as a Twitch streamer.