Finding records using Delegated Types

Hi,

I have a Delegated Types association set up like below and I need to find a particular Collection but the flickr_id is stored in the GalleryItem table. It's failing to return anything. How can I get the following line to work?

collection = Collection.find_by(flickr_id: flickr_collection.id)

-

class Collection < ActiveRecord::Base
    include GalleryItemable
end

-

class Album < ActiveRecord::Base
     include GalleryItemable
end

-

module GalleryItemable
    extend ActiveSupport::Concern

    included do
        has_one :gallery_item, as: :gallery_itemable, touch: true, dependent: :destroy
    end
end

-

class GalleryItem < ActiveRecord::Base
    belongs_to :collection, optional: true
    belongs_to :album, optional: true
    delegated_type :gallery_itemable, types: %w[ Collection Album ], dependent: :destroy

    acts_as_list scope: :collection
end

I hope someone can help.

Thanks,
Neil