title: Ruby gems won't load even though installed
body: <p>I know there's similar questions on SO, but none of them solve my problem...  The gist of it is that I can't get gems to load on a clean Ruby 1.9.1 install on Ubuntu 10.04:</p>
  
  <pre><code>:~/$ irb
  irb(main):001:0&gt; require 'rubygems'
  =&gt; false
  irb(main):002:0&gt; require 'cassandra'
  LoadError: no such file to load -- cassandra
      from (irb):1:in 'require'
      from (irb):1
      from /usr/local/bin/irb:12:in '&lt;main&gt;'
  irb(main):003:0&gt; Gem.path
  
  =&gt; ["/opt/ruby1.9/lib/ruby1.9/gems/1.9.1"]
  irb(main):004:0&gt; exit
  
  :~/$ ls /opt/ruby1.9/lib/ruby/gems/1.9.1/gems/
  cassandra-0.8.2  eventmachine-0.12.10  json-1.4.6  rake-0.8.7  simple_uuid-0.1.1  thrift-0.2.0.4  thrift-0.4.0  thrift_client-0.5.0
  
  :~/$ gem list --local
  
  *** LOCAL GEMS ***
  
  cassandra (0.8.2)
  eventmachine (0.12.10)
  json (1.4.6)
  rake (0.8.7)
  simple_uuid (0.1.1)
  thrift (0.4.0, 0.2.0.4)
  thrift_client (0.5.0)
  
  :~/$ gem env
  RubyGems Environment:
    - RUBYGEMS VERSION: 1.3.7
    - RUBY VERSION: 1.9.1 (2009-05-12 patchlevel 129) [x86_64-linux]
    - INSTALLATION DIRECTORY: /opt/ruby1.9/lib/ruby/gems/1.9.1
    - RUBY EXECUTABLE: /opt/ruby1.9/bin/ruby1.9
    - EXECUTABLE DIRECTORY: /opt/ruby1.9/bin
    - RUBYGEMS PLATFORMS:
      - ruby
      - x86_64-linux
    - GEM PATHS:
       - /opt/ruby1.9/lib/ruby/gems/1.9.1
       - /home/mark/.gem/ruby/1.9.1
    - GEM CONFIGURATION:
       - :update_sources =&gt; true
       - :verbose =&gt; true
       - :benchmark =&gt; false
       - :backtrace =&gt; false
       - :bulk_threshold =&gt; 1000
    - REMOTE SOURCES:
       - http://rubygems.org/
  </code></pre>
  
  <p>Any ideas?  Thanks in advance...</p>