re compiler & link passenger to nginx

just command ERROR :

nginx: [alert] Unable to start the Phusion Passenger watchdog because its executable (/home/xxx/.rvm/gems/ruby-2.1.2/gems/passenger-4.0.37/buildout/agents/PassengerWatchdog) does not exist. This probably means that your Phusion Passenger installation is broken or incomplete, or that your 'passenger_root' directive is set to the wrong value. Please reinstall Phusion Passenger or fix your 'passenger_root' directive, whichever is applicable. (-1: Unknown error)

FIX :

cd /home/xxx/.rvm/gems/ruby-2.1.2/gems/passenger-4.0.37/
rake nginx