error

/home/rege/.rvm/gems/ruby-1.9.2-p290/gems/sinatra-activerecord-0.1.3/lib/sinatra/activerecord.rb:4:in `require': no such file to load -- active_record (LoadError)
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/sinatra-activerecord-0.1.3/lib/sinatra/activerecord.rb:4:in `<top (required)>'
	from /home/rege/rails_projects/hksklep/hkshop.rb:2:in `require'
	from /home/rege/rails_projects/hksklep/hkshop.rb:2:in `block in <top (required)>'
	from /home/rege/rails_projects/hksklep/hkshop.rb:2:in `each'
	from /home/rege/rails_projects/hksklep/hkshop.rb:2:in `<top (required)>'
	from /home/rege/rails_projects/hksklep/config.ru:7:in `require'
	from /home/rege/rails_projects/hksklep/config.ru:7:in `block in <main>'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/builder.rb:51:in `instance_eval'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/builder.rb:51:in `initialize'
	from /home/rege/rails_projects/hksklep/config.ru:1:in `new'
	from /home/rege/rails_projects/hksklep/config.ru:1:in `<main>'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/builder.rb:40:in `eval'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/builder.rb:40:in `parse_file'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/server.rb:200:in `app'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/server.rb:301:in `wrapped_app'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/server.rb:252:in `start'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/lib/rack/server.rb:137:in `start'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.6/bin/rackup:4:in `<top (required)>'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/bin/rackup:19:in `load'
	from /home/rege/.rvm/gems/ruby-1.9.2-p290/bin/rackup:19:in `<main>'

Gemfile

source 'http://rubygems.org'
gem 'sinatra'
gem 'haml'
gem 'sass'
gem 'warden'
gem 'sinatra-activerecord'
gem 'rack', '1.3.6'
gem 'rack-flash'
group :development do
  gem 'guard-livereload'
end

gem 'heroku'

hkshop.rb

# encoding: UTF-8
%w[rubygems digest/md5 sinatra haml sass warden rack/flash sinatra/activerecord uri].each{ |gem| require gem }

set :root, File.dirname(__FILE__)
set :views, "views"

db = URI.parse(ENV['DATABASE_URL'] || 'postgres://localhost/mydb')

ActiveRecord::Base.establish_connection(
  :adapter  => db.scheme == 'postgres' ? 'postgresql' : db.scheme,
  :host     => db.host,
  :username => db.user,
  :password => db.password,
  :database => db.path[1..-1],
  :encoding => 'utf8'
)
get '/main.css' do
  header 'Content-Type' => 'text/css; charset=utf-8'
  sass :main
end

.....


  end
end

Rakefile

require './hkshop'
require 'sinatra/activerecord/rake'