我正在尝试使用Compass和Sass，安装了compass gem在三个版本的ruby（1.9.1、1.9.2、1.9.3）中，但每次都遇到同样的错误：
martin@crunchbang:~$ compass
/home/martin/.rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.3/lib/bundler/shared_helpers.rb:22:in `default_gemfile': Could not locate Gemfile (Bundler::GemfileNotFound)
from /home/martin/.rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.3/lib/bundler.rb:213:in `default_gemfile'
from /home/martin/.rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.3/lib/bundler.rb:164:in `root'
from /home/martin/.rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.3/lib/bundler.rb:123:in `load'
from /home/martin/.rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.3/lib/bundler.rb:114:in `setup'
from /home/martin/.rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.3/lib/bundler.rb:119:in `require'
from /home/martin/.rvm/gems/ruby-1.9.3-p194/gems/compass-0.12.1/bin/compass:25:in `<top (required)>'
from /home/martin/.rvm/gems/ruby-1.9.3-p194/bin/compass:19:in `load'
from /home/martin/.rvm/gems/ruby-1.9.3-p194/bin/compass:19:in `<main>'
from /home/martin/.rvm/gems/ruby-1.9.3-p194/bin/ruby_noexec_wrapper:14:in `eval'
from /home/martin/.rvm/gems/ruby-1.9.3-p194/bin/ruby_noexec_wrapper:14:in `<main>'
我该如何解决这个问题？
非常感谢您的帮助。