Hel using paperclip + imagemagick

I use paperclip to upload images and works great, but I am unable to resize them with imagemagick. All my photos are in system/public/photos and then in /11/original or 12/originial, for example. It is suppossed to be created a 11/small or 12/small directory, but it is nowhere. In my controller I have:

imagemagick_for "#{RAILS_ROOT}/public/system/photos"

I will appreciate any help

I get this when I try to open the img in another window: Image could not be processed. You have a nil object when you didn't expect it! You might have expected an instance of ActiveRecord::Base. The error occurred while evaluating nil.