twitter-bootstrap – 无法在twitter bootstrap中调用未定义错误

ActionView::Template::Error (Cannot call method 'charAt' of undefined
  (in /home/likewise-open/RADIXLOCAL/urjit.rajgor/workspace/twitter_bootstrap/app/assets/stylesheets/bootstrap_and_overrides.css.less)):
    11:       <script src="http://html5shim.googlecode.com/svn/trunk/html5.js" type="text/javascript"></script>
    12:     <![endif]-->
    13: 
    14:     <%= stylesheet_link_tag "application"  %>
    15: 
    16:     <link href="images/favicon.ico" rel="shortcut icon">
    17:     <link href="images/apple-touch-icon.png" rel="apple-touch-icon">
   app/views/layouts/application.html.erb:14:in `_app_views_layouts_application_html_erb__1043627680__634423168'
   app/controllers/posts_controller.rb:7:in `index'

我的Gemfile

source 'https://rubygems.org'

 gem 'rails','3.2.3'
 # Bundle edge Rails instead:
 # gem 'rails',:git => 'git://github.com/rails/rails.git'

 gem 'mysql2'
 gem "execjs"
 gem 'json'
 # Gems used only for assets and not required
 # in production environments by default.
gem "twitter-bootstrap-rails",:git => 'git://github.com/seyhunak/twitter-bootstrap-rails.git'
group :assets do
  gem 'sass-rails','~> 3.2.3'
  gem 'coffee-rails','~> 3.2.1'
  gem 'less-rails'
  # See https://github.com/sstephenson/execjs#readme for more supported runtimes
  gem 'therubyracer',:platform => :ruby
  gem 'uglifier','>= 1.0.3'

end
gem 'jquery-rails'

application.css

/*
 * This is a manifest file that'll automatically include all the stylesheets available  in this directory
 * and any sub-directories. You're free to add application-wide styles to this file and  they'll appear at
 * the top of the compiled file,but it's generally better to create a new file per style scope.
 *= require_self
 *= require bootstrap_and_overrides
 *= require_tree
 */

bootstrap_and_overrides.css.less

@import "twitter/bootstrap/bootstrap";
 body { padding-top: 60px; }

 @import "twitter/bootstrap/responsive";

// Set the correct sprite paths
 @iconSpritePath: asset-path('twitter/bootstrap/glyphicons-halflings.png');
 @iconWhiteSpritePath: asset-path('twitter/bootstrap/glyphicons-halflings-white.png');

 // Set the Font Awesome (Font Awesome is default. You can disable by commenting below lines)
 @fontAwesomeEotPath: asset-path('fontawesome-webfont.eot');
 @fontAwesomeWoffPath: asset-path('fontawesome-webfont.woff');
 @fontAwesomeTtfPath: asset-path('fontawesome-webfont.ttf');
 @fontAwesomeSvgzPath: asset-path('fontawesome-webfont.svgz');
 @fontAwesomeSvgPath: asset-path('fontawesome-webfont.svg');

// Font Awesome
@import "fontawesome";

帮我.
谢谢.