uninitialized constant Sass::Script::Functions::EvaluationContext

Hi, after deploying a bunch of modifications to my web app... I get the
error attached trying to load the page (see attached file). This is my
environment.rb file:

  config.gem 'warden'
  config.gem 'devise', "~> 1.0.9"
  config.gem "role_model"
  config.gem "formtastic", :version => "~> 0.9.10"
  config.gem 'searchlogic', :version => '~> 2.4.27'
  config.gem "haml", :version => ">=3.0.0"
  config.gem "friendly_id"
  config.gem "will_paginate"
  config.gem 'sanitize'
  config.gem "paperclip"
  config.gem 'fastercsv'
  config.gem 'validates_email_format_of'

  config.middleware.use "Sass::Plugin::Rack"

with rails 2.3.8... another application, with the same sass code and
environment, works fine! What's the deal?

Attachments:
http://www.ruby-forum.com/attachment/6773/haml_sass

did you already try

config.gem 'sass-rails'

?