Redmine

My problem is that i cant see attachments from my plugin, i added permission in init.rb but still shows the message : You are not authorized to access this page

My class:

class Unit < ActiveRecord::Base
    belongs_to :project

     acts_as_attachable :view_permission => :view_attachments, :delete_permission => :view_attachments
         .....
         ....
end

Init.rb

permission :view_attachments, {:attachments => [:edit,:show, :download, :thumbnail, :upload, :update, :destroy]}

i just dont know what i am missing