ruby on rails - image saved but missing using paperclip -

i using paperclip @ attach images offers in rails application. code works in development, not in staging. in staging, images saving correctly s3, image_file_name nil.

db/migrate/20130507182116_add_image_to_offers.rb

class addimagetooffers < activerecord::migration   def self.up     add_attachment :offers, :image   end    def self.down     remove_attachment :offers, :image   end end 

app/models/offer.rb

class offer < activerecord::base   attr_accessor :image    has_attached_file :image, styles: {     thumb: '100x100>',     square: '200x200#',     medium: '300x300>'   } 

when run following configuration in development mode works, when switch staging following error:

paperclip::error (offer model missing required attr_accessor 'image_file_name'): 

if add attr_accessor :image_file_name model completes , image saves s3, attribute nil in database.

be sure migrate database. also, if you're using heroku you'll need restart service: model missing required attr_accessor 'photo_file_name' when uploading paperclip , s3 on heroku