ActsAsFerret::IndexNotDefined

Hello!
I use acts_as_ferret at first.
I have several models with acts_as_ferret.
When I do search in the models User,Article,Therm it works fine.
But when I try search in Addition model or in Page model I got following
error message:
ActsAsFerret::IndexNotDefined
addition

in the string: @results = Addition.find_with_ferret(params[:q])

or
ActsAsFerret::IndexNotDefined
page

in the string: @results = Page.find_with_ferret(params[:q])

Where is mistake?
Thanks!

Problem solved.
Helped restarting ferret_server and rebuilding indexes for models