Topic: autotest returns with LoadError

Im using Linux Ubuntu and installed autotest as described here.

When I start autotest I always get this LoadError

$ autotest 
loading autotest/rails_rspec2
/home/sadik/.rvm/rubies/ruby-1.9.2-head/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': no such file to load -- test/unit/ui/console/testrunner (LoadError)
  from /home/sadik/.rvm/rubies/ruby-1.9.2-head/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
.
.
.
  from /home/sadik/.rvm/gems/ruby-1.9.2-head/bin/autotest:19:in `<main>'

why? Thanks for any help