title: Ruby: Cannot load such file from - LoadError
body: <p>I have a ruby script file with the name test.rb.</p>
  
  <p>the file has the following two require statements:</p>
  
  <pre><code>require 'oauth'
  require 'HTTParty'
  </code></pre>
  
  <p>I have the two gems already installed before.</p>
  
  <p>when running <strong>ruby test.rb</strong> in the terminal I get the following error:</p>
  
  <blockquote>
    <p>/opt/rubies/ruby-2.0.0-p598/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in
    <code>require': cannot load such file -- HTTParty (LoadError)
            from /opt/rubies/ruby-2.0.0-p598/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in
    </code>require'
            from test.rb:2:in `'</p>
  </blockquote>
  
  <p>what can be wrong here?</p>