"LoadError: no such file to load" when requiring gem

I'm using RVM, Ruby 1.9.2 and Rails 3.0.3 installed. I installed the curb-fu gem just now. When I do gem list, curb-fu is listed. When I do require 'curb-fu' in the irb, it returns true.

But when I try the same in the rails console of my app, I get this error:

ruby-1.9.2-p136 :001 > require 'curb-fu'
LoadError: no such file to load -- curb-fu

When I do require 'rubygems', it returns nil, and when I try curb-fu after that it gives the same error.

My gem environment:

RubyGems Environment:
  - RUBYGEMS VERSION: 1.3.7
  - RUBY VERSION: 1.9.2 (2010-12-25 patchlevel 136) [x86_64-darwin10.5.0]
  - INSTALLATION DIRECTORY: /Users/rits/.rvm/gems/ruby-1.9.2-p136
  - RUBY EXECUTABLE: /Users/rits/.rvm/rubies/ruby-1.9.2-p136/bin/ruby
  - EXECUTABLE DIRECTORY: /Use开发者_JAVA技巧rs/rits/.rvm/gems/ruby-1.9.2-p136/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-darwin-10
  - GEM PATHS:
     - /Users/rits/.rvm/gems/ruby-1.9.2-p136
     - /Users/rits/.rvm/gems/ruby-1.9.2-p136@global
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://rubygems.org/

What can I do?

You need to list the gem "curb-fu" in your app's Gemfile as

gem 'curb-fu'

and then run "bundle install".

In Rails 3, gem dependencies are handled thru Bundler and must be listed in the Gemfile.