TypeError: Mail is not a module

I have been stepping through the introduction of the Action Mailer
Basics page at:

I went through the steps through 2.1.3 Create a Mailer View (with
some variation of content)
I skipped 2.1.4, generating a user, since I already had a user class.

But I copied the line of code:

 UserMailer.welcome_email(@user).deliver

into my user controller in the context of an action, changing it to:

UserMailer.welcome_new_contact( tom, hagrid)

where the ‘tom’ and ‘hagrid’ are both users.

And I get this horrible error message:

 TypeError (Mail is not a module):
   app/mailers/user_mailer.rb:1:in `<top (required)>'
   app/controllers/users_controller.rb:285:in `mail_contact'
   app/controllers/users_controller.rb:409:in `add_contact'

Running if from the console gives me this error:

TypeError: Mail is not a module
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/actionmailer-3.1.0.rc6/lib/
action_mailer/tmail_compat.rb:1:in <top (required)>' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:237:in require’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/
active_support/dependencies.rb:237:in block in require' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:223:in block in load_dependency’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/
active_support/dependencies.rb:636:in new_constants_in' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:223:in load_dependency’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/
active_support/dependencies.rb:237:in require' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/actionmailer-3.1.0.rc6/lib/ action_mailer/base.rb:2:in <top (required)>’
from /opt/cmf/app/mailers/user_mailer.rb:3:in <top (required)>' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:452:in load’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/
active_support/dependencies.rb:452:in block in load_file' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:636:in new_constants_in’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/
active_support/dependencies.rb:451:in load_file' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:338:in require_or_load’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/
active_support/dependencies.rb:485:in load_missing_constant' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:181:in block in const_missing’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/
active_support/dependencies.rb:179:in each' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/activesupport-3.1.0.rc6/lib/ active_support/dependencies.rb:179:in const_missing’
from (irb):4
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/railties-3.1.0.rc6/lib/rails/
commands/console.rb:45:in start' from /opt/cmf/cloudfiles/ruby/1.9.1/gems/railties-3.1.0.rc6/lib/rails/ commands/console.rb:8:in start’
from /opt/cmf/cloudfiles/ruby/1.9.1/gems/railties-3.1.0.rc6/lib/rails/
commands.rb:40:in <top (required)>' from script/rails:6:in require’

Can anyone clue me in as to what is going on?