rethan, I edited it again. Use this one:

on !*:JOIN:%greetchan: {
  var %opnick = opnick1 opnick2 opnick3 opnick4 opnick5
  if (%greet == on) && (!$istok(%opnick,$nick,32)) { 
  .notice $nick 7 $nick Welcome to %greetchan 11 Have a nice 7 Chat 
  }
}
on !*:PART:%greetchan: {
  if (%greet == on) && ($nick isreg %greetchan) { 
  .notice $nick 7 $nick You left from %greetchan 11 cu 7 later 
  }
}