I'm unable to reproduce your effects.
Check to make sure you have appropriate access within the channel to match your script.
I "redid" your this to make:
Code:
on *^:TEXT:!setevent*:#:{
  if ($nick isreg $chan) || ($nick isvoice $chan) { halt }
  else {
    set %event $2-
    msg $chan The current event has been set to : %event .
  }
}
on $^1:TEXT:/^!(event|events)/iS:#:{
  if ($nick isreg $chan) { notice $nick Voice or higher only. | halt }
  else { notice $nick 8,2The event today is %event . }
}

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