为什么rails_admin没有加载设计

Question

我只是在我的rails应用程序中安装rails_admin ....但我没有加载或显示设计页面....发生了什么......？

Route.rb

ForestBankPakistan::Application.routes.draw do

  mount RailsAdmin::Engine => '/admin', :as => 'rails_admin'
  resources :forests

  devise_for :admins, :controllers => { :registrations => "admin/registrations", :sessions => "admin/sessions", :passwords => "admin/passwords" }

  get "main/index", :to => "main#index", as: :main_index
  get "main/projects", :to => "main#projects", as: :main_projects
  get "main/publications", :to => "main#publications", as: :main_publications
  get "main/forestInPakistan", :to => "main#forestInPakistan", as: :main_forestInPakistan
  get "main/eventCalanders", :to => "main#eventCalanders", as: :main_eventCalanders
  get "main/aboutUs", :to => "main#aboutUs", as: :main_aboutUs
  get "main/new", :to => "main#new", as: :main_new
  post "main/createNews"

  root to: "main#index", :to => "main#index"
  # The priority is based upon order of creation: first created -> highest priority.
  # See how all your routes lay out with "rake routes".

  # Events
  get "event/index", :to => "event#index", as: :event_index
  get "event/show/:id", :to => "event#show", as: :event_show
  get "event/new", :to => "event#new", as: :event_new
  get "event/edit/:id", :to => "event#edit", as: :event_edit
  post "event/createEvent"
  post "event/updateEvent/:id", :to => "event#updateEvent", as: :event_update
  delete "event/destroy/:id", :to => "event#destroy", as: :event_destroy

  # Donation
  get "donation/new", :to => "donation#new", as: :donation_new
  get "donation/edit", :to => "donation#edit", as: :donation_edit
  get "donation/show", :to => "donation#show", as: :donation_show
  get "donation/index", :to => "donation#index", as: :donation_index
  post "donation/createDonation"

  # Route for Devise
  devise_scope :admin do
  end

end

设计模型

class Admin < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable
end

发生了什么......我不明白....有些人可以帮助我摆脱这个......？