Paperclip Upload to S3 with Delayed Job - ruby-on-rails

Question

I am trying to upload a file to s3 in background using Rails (4.2) with delayed_job gem.
My code is basically what is shown in this post:http://airbladesoftware.com/notes/asynchronous-s3/ (with small changes).
The Photo Modal
class Photo < ActiveRecord::Base
belongs_to :gallery
has_attached_file :local_photo,
path: ":rails_root/public/system/:attachment/:id/:style/:basename.:extension",
url: "/system/:attachment/:id/:style/:basename.:extension"
has_attached_file :image,
styles: {large: '500x500#', medium: '180x180#'},
storage: :s3,
s3_credentials: lambda { |attachment| attachment.instance.s3_keys },
s3_permissions: :private,
s3_host_name: 's3-sa-east-1.amazonaws.com',
s3_headers: {'Expires' => 1.year.from_now.httpdate,
'Content-Disposition' => 'attachment'},
path: "images/:id/:style/:filename"
validates_attachment_content_type :image,
content_type: [
"image/jpg",
"image/jpeg",
"image/png"]
def s3_keys
{
access_key_id: SECRET["key_id"],
secret_access_key: SECRET["access_key"],
bucket: SECRET["bucket"]
}
end
after_save :queue_upload_to_s3
def queue_upload_to_s3
Delayed::Job.enqueue ImageJob.new(id) if local_photo? && local_photo_updated_at_changed?
end
def upload_to_s3
self.image = Paperclip.io_adapters.for(local_photo)
save!
end
end
class ImageJob < Struct.new(:image_id)
def perform
image = Photo.find(image_id)
image.upload_to_s3
image.local_photo.destroy
end
end
With this code, the job (ImageJob) run in background (I can see it on delayed_job_web), no error. But the file is not uploaded.
If I "disable background" and use only:
ImageJob.new(id).perform if local_photo? && local_photo_updated_at_changed?
The file is uploaded to the amazon and local file is deleted too.
Any suggestions ?
Thanks in advance
UPDATE #1 Now I can see the error:
Job failed to load: undefined class/module ImageJob. Handler: "--- !ruby/struct:ImageJob\nimage_id: 412\n"
UPDATE #2 I make this working using delay method, something like this:
def perform
if local_photo? && local_photo_updated_at_changed?
self.delay.move_to_s3
end
end