安装vote_fu_rails_3 gem的问题

Question

我正在尝试为rails 3安装vote_fu_rails_3 gem。我运行了命令：

    $ rails plugin install git://github.com/vshvedov/vote_fu_rails_3.git

我在这里找到了：

https://github.com/vshvedov/vote_fu_rails_3

没有对项目进行任何更改，运行命令后出现此错误：

    C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.8/lib/rails/commands/plugin.rb:
    277:in `<top (required)>': Commands is not a module (TypeError)
    from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activesupport-3.0.8/lib/active_          
    support/dependencies.rb:239:in `require'
    from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activesupport-3.0.8/lib/active_
    support/dependencies.rb:239:in `block in require'
    from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activesupport-3.0.8/lib/active_
    support/dependencies.rb:225:in `block in load_dependency'
    from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activesupport-3.0.8/lib/active_
    support/dependencies.rb:596:in `new_constants_in'
    from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activesupport-3.0.8/lib/active_
    support/dependencies.rb:225:in `load_dependency'
    from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activesupport-3.0.8/lib/active_
    support/dependencies.rb:239:in `require'
    from C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.8/lib/rails/comman
    ds.rb:17:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

它说命令不是一个模块。有人可以帮忙吗？我在Windows 7上运行。非常感谢，谢谢。