Rails 3应用程序中的Sass导入错误-“找不到或无法读取的导入文件：罗盘”

我有一个成功运行过的Rails 3应用程序compass init rails ./ --using blueprint。我可以@import从/ stylesheets目录中归档文件，但是尝试时出现错误@import compass。

现在，该应用程序具有两个简单的sass文件：

common.scss

$body-background: blue;

main.scss

@import "common";
//@import "compass";

body { 
  background: $body-background; 
}

@import "compass"注释掉该行后，此方法有效-我得到了蓝色背景，所以我知道Sass在起作用。

如果我取消注释该行，并尝试导入compass或blueprint其他任何内容，则会收到这样的错误。

Syntax error: File to import not found or unreadable: compass.
              Load paths:

                /Users/eric/path/to/myrailsapp/app/stylesheets
        on line 2 of /Users/eric/path/to/myrailsapp/app/stylesheets/main.scss

1: @import "common";
2: @import "compass";
3: 
4: body { 
5:  background: $body-background; 
6: }

我可能不得不明确地告诉Sass在哪里可以找到Compass gem，所以我add_import_path在config / compass.rb中添加了一行：

require 'compass'
require 'html5-boilerplate'

project_type = :rails
project_path = RAILS_ROOT if defined?(RAILS_ROOT)
add_import_path "/Library/Ruby/Gems/1.8/gems/"  # unfortunately this has no effect

http_path = "/"
css_dir = "public/stylesheets"
sass_dir = "app/stylesheets"
images_dir = "public/images"
javascripts_dir = "public/javascripts"
cache_dir = "tmp/sass-cache"

http_images_path = "/images"
http_stylesheets_path = "/stylesheets"
http_javascripts_path = "/javascripts"

我已经搜寻了两天，无法确定为什么我的基本@import陈述会出现这个问题。如何告诉Sass在哪里可以找到Compass和Blueprint库？