Unable to create spree extension - unable to activate rails-3.2.4 activesupport version conflicts

Unable to create spree extension - unable to activate rails-3.2.4
activesupport version conflicts

I'm a newbie to Ruby/Rails/Spree and am trying to follow this tutorial
http://guides.spreecommerce.com/developer/extensions_tutorial.html#creating-an-extension
to create a simple spree extension.
I enter this command:
spree extension simple_sales
and cd into spree_simple_sales
Any rails command I type now within this directory (eg. rails -v) results
in this error:
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:1637:in
`raise_if_conflicts': Unable to activate rails-3.2.4, because
activesupport-4.0.0 conflicts with activesupport (= 3.2.14),
actionpack-4.0.0 conflicts with actionpack (= 3.2.14), railties-4.0.0
conflicts with railties (= 3.2.14), activerecord-4.0.0 conflicts with
activerecord (= 3.2.14), actionmailer-4.0.0 conflicts with actionmailer (=
3.2.14) (Gem::LoadError)
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:746:in
`activate'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:780:in
`block in activate_dependencies'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:766:in
`each'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:766:in
`activate_dependencies'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:750:in
`activate'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:780:in
`block in activate_dependencies'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:766:in
`each'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:766:in
`activate_dependencies'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:750:in
`activate'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems.rb:212:in
`rescue in try_activate'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems.rb:209:in
`try_activate'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:59:in
`rescue in require'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in
`require'
from D:/Dev/Tests and
Tutorials/rails/extensions/spree_simple_sales/lib/spree_simple_sales/engine.rb:3:in
`<class:Engine>'
from D:/Dev/Tests and
Tutorials/rails/extensions/spree_simple_sales/lib/spree_simple_sales/engine.rb:2:in
`<module:SpreeSimpleSale>'
from D:/Dev/Tests and
Tutorials/rails/extensions/spree_simple_sales/lib/spree_simple_sales/engine.rb:1:in
`<top (required)>'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in
`require'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in
`require'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-4.0.0/lib/rails/engine/commands.rb:11:in
`<top (required)>'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in
`require'
from
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in
`require'
from script/rails:7:in `<main>'
What can I do to fix this? I am on Win 7, have used RailsInstaller to
install Ruby 1.9.3. I have both Rails 4.0.0 and 3.2.14 but am using Rails
3.2.14 with Spree. Thanks!