help with auto_complete modifiction

Hi -

I'm trying to modify auto_complete_for to allow a foreign table to be
the source of the lookup strings. It's currently defined as:

def auto_complete_for(object, method, options = {})

which tells me I can simply add a "foreign" argument at the end of my
call and it will be auto-added to the options array (is this right?).

So, now I change:

@items = object.to_s.camelize.constantize.find(:all, find_options)

to

options[:foreign] ? @items =
options[:foreign].to_s.camelize.constantize.find(:all, find_options) :
@items = object.to_s.camelize.constantize.find(:all, find_options)

And in my controller, I call:

auto_complete_for :story, :tag_holder, :foreign => 'tag'

But i get this error in the log:

ArgumentError (Unknown key(s): foreign):

Can someone explain options hash and what's wrong here?

Thanks,
Dino