I cant see how that script ever worked. maybe use the following.

Code:
on 500:text:!nick*:?: {
  if (!$2) || ($2 === $me) { .msg $nick $iif($ifmatch == $me,i already have that nick,Syntax: /msg $me nick <nickname to use>.) | return }
  nick $2 | .msg $nick Nick change completed.
}