Do you get any messages in your status or channel windows? Are you typing this on a channel that both you and the bot are on? You need to type it in a different instance of mIRC to what the script is running in.

Try changing it to this:

Code:
on *:text:!connect:#:{
  echo -s /join $chr(35) $+ $nick
}


And see if anything is echoed in your status window. If so, what does it say?