Issue with Deploying a Rails app on VPS - cannot load such file -- unicorn/launcher

I am trying to deploy a rails application to a digitalocean VPS droplet. I have the following setup Ruby on Rails on Ubuntu 12.10 (Nginx + Unicorn). I have installed Ruby ruby-2.0.0-p247 and rails Rails 4.0.0 via rvm but when I try to restart Unicorn I get the following error.

/usr/local/rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require’: cannot load such file – unicorn/launcher (LoadError)

from /usr/local/rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'

from /usr/bin/unicorn:3:in `<main>'

Could it be because if my GEM_HOME and GEM_PATH are different?

$GEM_PATH

/usr/local/rvm/gems/ruby-2.0.0-p247:/usr/local/rvm/gems/ruby-2.0.0-p247@global

$GEM_HOME

/usr/local/rvm/gems/ruby-2.0.0-p247

Any help would very much appreciated.

Have you tried re-installing(bundle install) the gem under the gemset/ruby you’re currently using?
it seems that unicorn was not installed correctly or is not installed at all.