rake validate_guides what am I missing?

Guys I get the following error when I run rake validate_guides, what am I missing? Thanks!

yadav@Six9:$ rake validate_guides
(in /home/yadav/dev/docs/RailsGuides/docrails/railties)
/usr/local/bin/ruby guides/w3c_validator.rb
<internal:lib/rubygems/custom_require>:29:in `require': no such file to load -- w3c_validators (LoadError)
         from <internal:lib/rubygems/custom_require>:29:in `require'
         from guides/w3c_validator.rb:30:in `<main>'
rake aborted!
Command failed with status (1): [/usr/local/bin/ruby guides/w3c_validator.r...]
/usr/local/lib/ruby/1.9.1/rake.rb:993:in `block in sh'
/usr/local/lib/ruby/1.9.1/rake.rb:1008:in `call'
/usr/local/lib/ruby/1.9.1/rake.rb:1008:in `sh'
/usr/local/lib/ruby/1.9.1/rake.rb:1092:in `sh'
/usr/local/lib/ruby/1.9.1/rake.rb:1027:in `ruby'
/usr/local/lib/ruby/1.9.1/rake.rb:1092:in `ruby'
/home/yadav/dev/docs/RailsGuides/docrails/railties/Rakefile:55:in `block in <top (required)>'
/usr/local/lib/ruby/1.9.1/rake.rb:634:in `call'
/usr/local/lib/ruby/1.9.1/rake.rb:634:in `block in execute'
/usr/local/lib/ruby/1.9.1/rake.rb:629:in `each'
/usr/local/lib/ruby/1.9.1/rake.rb:629:in `execute'
/usr/local/lib/ruby/1.9.1/rake.rb:595:in `block in invoke_with_call_chain'
/usr/local/lib/ruby/1.9.1/monitor.rb:201:in `mon_synchronize'
/usr/local/lib/ruby/1.9.1/rake.rb:588:in `invoke_with_call_chain'
/usr/local/lib/ruby/1.9.1/rake.rb:581:in `invoke'
/usr/local/lib/ruby/1.9.1/rake.rb:2041:in `invoke_task'
/usr/local/lib/ruby/1.9.1/rake.rb:2019:in `block (2 levels) in top_level'
/usr/local/lib/ruby/1.9.1/rake.rb:2019:in `each'
/usr/local/lib/ruby/1.9.1/rake.rb:2019:in `block in top_level'
/usr/local/lib/ruby/1.9.1/rake.rb:2058:in `standard_exception_handling'
/usr/local/lib/ruby/1.9.1/rake.rb:2013:in `top_level'
/usr/local/lib/ruby/1.9.1/rake.rb:1992:in `run'
/usr/local/bin/rake:31:in `<main>'

Hi Rajinder, you need to install the w3c_validators gem

Hi Jaime, thank you!