Redmine

All,
We have setup a new redmine server using the latest 1.2.1 download. We are trying to test incoming email using the following"

rake -f /var/redmine/Rakefile redmine:email:receive_imap unknown_user=accept no_permission_check=1 RAILS_ENV="production" host=imap.gmail.com port=993 username=<our email address> password=<our password> ssl=1 project=ivr tracker=support --trace

We are getting the following output:
(in /var/redmine/vendor/rails/railties)
rake aborted!
no such file to load -- rdoc/task
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
/var/redmine/Rakefile:9
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2383:in `load'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2383:in `raw_load_rakefile'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2017:in `load_rakefile'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2016:in `load_rakefile'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2000:in `run'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:1998:in `run'
/usr/lib/ruby/gems/1.8/gems/rake-0.8.7/bin/rake:31
/usr/bin/rake:19:in `load'
/usr/bin/rake:19

I have tried to uninstall and reinstall rake, however this caused no change. I version requirements match http://www.redmine.org/projects/redmine/wiki/RedmineInstall for the latest build.
ruby 1.8.7 (2010-06-23 patchlevel 299) [x86_64-linux]
rack (1.1.1)
rails (2.3.11)
rake (0.8.7)

Any advise you could supply would be greatly appreciated.

Thanks in advances,

Jes