Please help! ActiveAdmin: not saving association between my two models (Rails)

[martinbortowski]

I have two models a room and a photo model. In the ActiveAdmin I want to update the association between the photo and the room.

room.rb (app/models)

class Room < ApplicationRecord
    has_many :photos
    accepts_nested_attributes_for :photos
end

photo.rb (app/models)

class Photo < ApplicationRecord
  belongs_to :room

  has_attached_file :image, styles: { medium: "300x300>", thumb: "100x100>" }
  validates_attachment_content_type :image, content_type: /\Aimage\/.*\z/
end

room.rb (app/admin)

ActiveAdmin.register Room do
    permit_params :listing_name, :type, :persons, :property, :living_area,
    :rooms_total, :features_short, :pets, :smoking, :check_in, :check_out,
    :location, :distance, :features_long, :detailed_description, :house_rules,
    :address, :video, :nightly_price, :hourly_price, :detailed_price, :active, 
    :photo_id,
end

photo.rb (app/admin)

ActiveAdmin.register Photo do
   permit_params :image, , rooms_attributes: [:id, :listing_name]

   index do
    selectable_column
    id_column
    column :image_file_name
    column :listing_name
    column :room
    column :updated_at
    column :created_at
    actions
  end

   show do |image|
      attributes_table do
         row :image do
            photo.image? ? image_tag(photo.image.url, height: '100') : content_tag(:span, "No photo yet")
         end
      end
      active_admin_comments
   end

  form :html => { :enctype => "multipart/form-data" } do |f|
     f.inputs do
        f.input :image, hint: f.photo.image? ? image_tag(f.photo.image.url, height: '100') : content_tag(:span, "Upload JPG/PNG/GIF image")
     end
     f.inputs do
       f.collection_select :room, Room.all,:id,:listing_name
     end
  f.actions
end

The form seems to work but it does not save it to the database when I check the record(last room) in the rails console it always returns me room_id: nil? I have tried everything nothing seems to work this drives me nuts. Any hints welcomed! If someone needs further information just let me know.