run RailsServer on aptana studio 3

hi
i want to run my ruby application on aptana studio 3.0 : when i run the
railsserver i have this message :
C:/Ruby200/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:106:in
`require': cannot load such file -- initializer (LoadError)
  from
C:/Ruby200/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:106:in
`require'
  from C:/Dev/Aptana/bibliotheque/config/boot.rb:55:in
`load_initializer'
  from C:/Dev/Aptana/bibliotheque/config/boot.rb:38:in `run'
  from C:/Dev/Aptana/bibliotheque/config/boot.rb:11:in `boot!'
  from C:/Dev/Aptana/bibliotheque/config/boot.rb:110:in `<top
(required)>'
  from
C:/Ruby200/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in
`require'
  from
C:/Ruby200/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in
`require'
  from C:/Dev/Aptana/bibliotheque/script/server:2:in `<main>'

Have you an idea?