Rails : Unpermitted parameter: :track_ids with complex form

I would like to create a Town who have several neested attributes :

My controller :

def new
  @town = Town.new(params[:user_id])
  @user = current_user.id if current_user
  @poi = @town.build_poi(user_id: @user)
  @track = @town.poi.tracks.build
end

def create
  @town = Town.new(town_params)
  @town.user_id = current_user.id if current_user
  if @town.save(town_params)
    if params[:images]
      params[:images].each do |image|
        @town.town_images.create(image: image)
      end
    end
  redirect_to root_path, notice: t(".town_created")
  else
    render :new
  end
end

And my strong params :

def town_params
  params.require(:sleep).permit(
    :name,
    :user_id,
    { :service_ids => [] },
    { :poi_attributes => [:id,  :city, :pk, :latitude, :longitude,  :poitable_id, :poitable_type, :user_id, :track_ids =>[] ] },
    { :image_attributes => [:image, :town_id]})
end

I get the following error : Unpermitted parameter: :track_ids

I try to use permit! but I always have the same error. What's wrong ?