Question: I have an API system I am working on and am in need of a quick admin section for simple CRUD actions. So I decided to install ActiveAdmin, but when I go to <http://localhost:3000/admin/login>, I am getting a 406 unacceptable log error and a white screen.

I followed the instructions provided by activeadmin, but it's not working. Anyone else run into this issue?

Here are my routes:

```
TestApp::Application.routes.draw do
  ActiveAdmin.routes(self)

  devise_for :admin_users, ActiveAdmin::Devise.config

  namespace "api" do
    namespace "v1" do

      resources :countries do
        resources :states
      end

      resources :states do
        resources :counties
      end

      resources :counties do
        resources :districts
      end

      resources :districts do
        resources :schools
      end

    end # end v1 Namespace
  end # end api Namespace
end # end TestApp::Application routes

```

Answer: 
Just for reference in case it helps anyone, I had this same issue with ActiveAdmin `0.6.3`. I was getting this log entry when trying to update a resource:

```
Started PUT "/admin/brands/117" for 127.0.0.1 at 2014-04-16 13:01:22 -0300
Processing by Admin::BrandsController#update as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"[FILTERED]", "brand"=>{"key"=>"Somebrand"}, "commit"=>"Update Brand", "id"=>"117"}
  AdminUser Load (1.1ms)  SELECT "admin_users".* FROM "admin_users" WHERE "admin_users"."id" = 1 LIMIT 1
  Brand Load (1.0ms)  SELECT "brands".* FROM "brands" WHERE "brands"."id" = $1 LIMIT 1  [["id", "117"]]
Completed 406 Not Acceptable in 216.9ms (ActiveRecord: 2.1ms)

```

Turns out the attributes were not accessible in the `Brand` model, so Rails decided to return a `406`.
this solve my problem

```
gem 'activeadmin' , '0.4.2'
gem "formtastic", "~> 2.1.1"

```