The @ and % prefixes are only required if you want certain commands to be done when the bot has a certain level. Eg: setting a channel mode, voicing a user, etc.
I can't see anything wrong with the original .notice line, but it seems like the first occurance of $nick in that line is being ignored, so the server thinks it's seeing .notice Hello $nick rather than .notice $nick Hello $nick
That's why that error was coming up, now as to how to fix it, the only thing I can think of is to manually re-write that line, so that we're sure there aren't any hidden codes being transfered in a copy/paste.
