Geokit in Ruby on Rails, problem with acts_as_mappable

i have looked through the list of related questions however my problem does not seem to be listed and hence here it is:

Basically I'm trying to use Geokit within the Ruby on Rails environment, im not sure if i installed it properly, I have included it within the environment.rb (and done rake db:install) and i'm now trying to do the following:

require 'active_record'
require 'geokit'

class Store < ActiveRecord::Base
    acts_as_mappable
end

Unforunately, when i try to run this and see if its ok, i get the following error:

c:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/base.rb:1959:in `method_missing': undefined local variable or method `acts_as_mappable' for #<Class:0x4cd261c> (NameError)
    from C:/Users/Erika/Documents/Visual Studio 2008/Projects/StoreLocator/StoreLocator/app/models/store.rb:5

I am running Ruby in Steel for Visual Studio 2008, i'm not sure what i'm doing wrong as all the online tutorials i find tend to be rather old and done apply to me. Any help would be greatly appreciated. thanks!

Edit: (adding as per Ben's Request) The following is what my environment.rb looks like

# Be sure to restart your server when you modify this file

# Specifies gem version of Rails to use when vendor/rails is not present
RAILS_GEM_VERSION = '2.3.4' unless defined? RAILS_GEM_VERSION

# Bootstrap the Rails environment, frameworks, and default configuration
require File.join(File.dirname(__FILE__), 'boot')

Rails::I开发者_StackOverflownitializer.run do |config|
  # Settings in config/environments/* take precedence over those specified here.
  # Application configuration should go into files in config/initializers
  # -- all .rb files in that directory are automatically loaded.

  # Add additional load paths for your own custom dirs
  # config.load_paths += %W( #{RAILS_ROOT}/extras )

  # Specify gems that this application depends on and have them installed with rake gems:install
  # config.gem "bj"
  # config.gem "hpricot", :version => '0.6', :source => "http://code.whytheluckystiff.net"
  # config.gem "sqlite3-ruby", :lib => "sqlite3"
  # config.gem "aws-s3", :lib => "aws/s3"
  config.gem "geokit"
  config.gem "ym4r"

  # Only load the plugins named here, in the order given (default is alphabetical).
  # :all can be used as a placeholder for all plugins not explicitly named
  # config.plugins = [ :exception_notification, :ssl_requirement, :all ]

  # Skip frameworks you're not going to use. To use Rails without a database,
  # you must remove the Active Record framework.
  # config.frameworks -= [ :active_record, :active_resource, :action_mailer ]

  # Activate observers that should always be running
  # config.active_record.observers = :cacher, :garbage_collector, :forum_observer

  # Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
  # Run "rake -D time" for a list of tasks for finding time zone names.
  config.time_zone = 'UTC'

  # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
  # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}')]
  # config.i18n.default_locale = :de
end

# These defaults are used in GeoKit::Mappable.distance_to and in acts_as_mappable
GeoKit::default_units = :kms
GeoKit::default_formula = :sphere

# This is the timeout value in seconds to be used for calls to the geocoder web
# services.  For no timeout at all, comment out the setting.  The timeout unit
# is in seconds. 
#GeoKit::Geocoders::timeout = 3

# These settings are used if web service calls must be routed through a proxy.
# These setting can be nil if not needed, otherwise, addr and port must be 
# filled in at a minimum.  If the proxy requires authentication, the username
# and password can be provided as well.
GeoKit::Geocoders::proxy_addr = nil
GeoKit::Geocoders::proxy_port = nil
GeoKit::Geocoders::proxy_user = nil
GeoKit::Geocoders::proxy_pass = nil

# This is your yahoo application key for the Yahoo Geocoder.
GeoKit::Geocoders::yahoo = 'REPLACE_WITH_YOUR_YAHOO_KEY'

# This is your Google Maps geocoder key. 
GeoKit::Geocoders::google = 'apikey'

# This is your username and password for geocoder.us.
# To use the free service, the value can be set to nil or false.  For 
# usage tied to an account, the value should be set to username:password.
GeoKit::Geocoders::geocoder_us = false 

# This is your authorization key for geocoder.ca.
# To use the free service, the value can be set to nil or false.  For 
# usage tied to an account, set the value to the key obtained from
# Geocoder.ca.

GeoKit::Geocoders::geocoder_ca = false

# This is the order in which the geocoders are called in a failover scenario
# If you only want to use a single geocoder, put a single symbol in the array.
# Valid symbols are :google, :yahoo, :us, and :ca.
# Be aware that there are Terms of Use restrictions on how you can use the 
# various geocoders.  Make sure you read up on relevant Terms of Use for each
# geocoder you are going to use.
GeoKit::Geocoders::provider_order = [:google]

acts_as_mappable is part of geokit-rails. You need to install the geokit-rails plugin.

script/plugin install git://github.com/andre/geokit-rails.git

To check if the plugin is properly installed, look under the vendor/plugins directory of your Rails app. It should have a geokit-rails sub directory. It it, you'll find all the plugin files, other subdirectories, including the file acts_as_mappable.rb (in vendor\plugins\geokit-rails\lib\geokit-rails).

If everything seems to be properly installed, try adding "require geokit" to the top of the init.rb file in the plugin root folder (vendor\plugins\geokit-rails).

Be sure to restart your app server after making the modifications.

What method are you using to include the geokit library? The plugin? The gem? Is the gem unpacked into vendor? What does your environment.rb look like?

Edit: I meant to leave this as a comment on the question - pardon me.