title: Rack/Sinatra LoadError: cannot load such file
body: <p>I'm trying to build an app using Sinatra, Ruby, rack, haml, pony and SendGrid, with git and RVM for deployment on Heroku. The app is a blog variant that should send out an email with commentary submitted on a form. On my local server, when the form submits I get the following error:</p>
  
  <pre><code>LoadError at /
  cannot load such file -- pony
  file: tools.rb location: require line: 314
  BACKTRACE
  (expand)
  /Users/Kevin/prog/ruby/Sinatra/Noobs/noobs.rb in block in &lt;top (required)&gt;
    require 'pony'
  </code></pre>
  
  <p>When run on Heroku, form submittal results in an internal server error. The 'cannot load such file' error suggests that the file is not on the gem path, but if I understand correctly, the OS disagrees:</p>
  
  <pre><code>➜  noobs git:(master) ✗ bundle show pony
  /Users/Kevin/.rvm/gems/ruby-1.9.3-p194@noobs/gems/pony-1.4
  
  ➜  noobs git:(master) echo $GEM_PATH
  /Users/Kevin/.rvm/gems/ruby-1.9.3-p194@noobs:/Users/Kevin/.rvm/gems/ruby-1.9.3-p194@global
  </code></pre>
  
  <p>Here is the code where pony is required (noobs.rb):</p>
  
  <pre><code>require 'rubygems'
  require 'sinatra'
  require 'haml'
  require "sinatra/reloader" if development?  
  
  # ...
  
  post '/' do
    require 'pony'
    Pony.mail(:from =&gt; params[:name] + "&lt;" + params[:contact] + "&gt;",
  </code></pre>
  
  <p>What do I need to do to get pony to work?</p>