Less::ParseError in Home#index

Showing /Users/burtondav/sites/requestsys/app/views/layouts/application.html.erb where line #20 raised:

Cannot call method 'charAt' of undefined
  (in /Users/burtondav/sites/requestsys/app/assets/stylesheets/bootstrap_and_overrides.css.less)
Extracted source (around line #20):

17:       }
18:   </style>
19: 
20:   <%= stylesheet_link_tag "application",:media => "all" %>

我正在使用的一些GEMS：

gem 'rails','3.2.11'
gem 'twitter-bootstrap-rails'
group :assets do
  gem 'sass-rails','~> 3.2.3'
  gem 'coffee-rails','~> 3.2.1'
  gem 'less-rails'
  gem 'commonjs'
  gem 'therubyracer',:platforms => :ruby
  gem 'uglifier','>= 1.0.3'

end

这似乎是Bootstrap使用的LESS问题.

我读过其他几个类似的问题.所以,我将Ruby升级到1.9.3p374.但是,这并没有解决问题.

有任何想法吗？

谢谢！

UPDATE

这是bootstrap_and_overrides.css.less

@import "twitter/bootstrap/bootstrap";
@import "twitter/bootstrap/responsive";

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