index_format

[Jason Majors]

I'm trying to change my index_format for my $record mailbox to show the 
recipient, not my address.
I changed the index_format variable like it says in the online doc. When I input
it at the colon prompt it works fine, but when I try it using a folder-hook
it complains about some of the format strings %F, %Z and a few others.
Does anybody know why this might be?
Thanks
jason majors