Commands prefixed with ! are script commands because they trigger with an on text event (see
/help on text). You can download scripts from sites such as
www.mircscripts.org and
www.mirc.net too - they should come with instructions on how to correctly install them into mIRC.
If you already have a script, make sure it's loaded correctly and make sure your remotes are on by typing
/remote on. Also remember that you cannot use on text commands on yourself they can only be triggered by a separate client.
Hope this helps a little
Regards,