/help IAL
Read about how and WHAT the IAL stores, especially what it doesn't.. a common oversight is for people to overlook the fact that doing a lookup in the IAL does *not* guarantee that you will get a result for the nickname in question. A user is only added to the ial when:
1. they are involved in an IRC action that lists their hostname along with their username (PRIVMSG, MODE, CTCP, WHOIS REPLIES, WHO REPLIES)
2. they are *still* on a common channel with you
Pay close attention to #1, because when you join a channel, 99% of the users have not yet been involved in actions that list their usernames unless you explicitly /who the channel.
Long story short: it's your responsibility to keep your IAL up to date and realize when it is feasible to use it... if your script uses $2 as nicknames you don't share channels with, it will never work. If $2 can be any user in the channel, you have to make sure you keep your IAL up to date by looking at every user's hostname when you join a channel. This can be done with /who, and there are other methods too.
Think of the IAL as a cache, not a database. It will only return results for nicknames you've already seen, so it is not a good way to do lookups.
PS. Your hdel command is failing because $ial returns $null, since it had no info on $2 (if you didn't get that part yet)
