Issue with paperclip-dropbox, not show images in records

I have web app, I connect it with paperclip-dropbox. Upload works good, but i can't open images on my app. When i try open image i get web address: http://ift.tt/1N2WSMh and issue: "It seems you don't belong here! You should probably sign in. Check out our Help Center and forums for help, or head back to home. "

model:

class Message < ActiveRecord::Base

  has_attached_file :avatar, :styles => { :medium => "300x300>", :thumb => "150x150>" },
  :storage => :dropbox,
      :dropbox_credentials => Rails.root.join("config/dropbox.yml"),
      :dropbox_visibility => 'public'

  validates_attachment_content_type :avatar, :content_type => /\Aimage\/.*\Z/


  validates_presence_of :topic, content:   "- Dopisz"

end