ActiveAdmin Error: no superclass method `buttons'

I had same problem and it's killed my about hours.

I am using rails 4 and active admin form master git:

gem 'activeadmin', github: 'gregbell/active_admin'

I just used "f.actions" instead of "f.buttons"

form do |f|
  f.inputs "Enter Todo details" do
    f.input :quote_id, :as => :select, :collection => Quote.all.map {|q| [ q.contact,q.id]}, :include_blank => false 
    f.input :name, :label => "Name of customer"
    f.input :state, :as => :select, :collection => ['Active','Closed'], :include_blank => false
    f.input :moving_date
    f.input :revisit
    f.input :address
    f.input :status
  end
  f.actions
end

It's works for me.

For Rails 4+

If you are running Rails 4+ use f.actions instead of f.buttons. Here's an issue that talks about this change on the ActiveAdmin repo https://github.com/activeadmin/activeadmin/issues/1085

Original answer for OP question in 2012

seems like formtastic 2.2.0 (released today) breaks active_admin and since active_admin requires formtastic >= 2.0.0... put in your Gemfile this

gem "formtastic", "~> 2.1.1"
gem "activeadmin", "~> 0.4.3"

then run

bundle update formtastic

then restart your server (if you have it running)..

and should work ok...