You have your $istok backwards.
$istok(list of tokens,token to search for from list,separator)
It's easy to get it backwards based on the help file description because token is the second item, not the first in the help file. However, when it's referring to the token, it's referring to what you're searching for in the original string (aka list of tokens).
$istok(nick1 nick2 nick3,$nick,32)