Can't get Growl notifications working with growl-rspec gem

I have the "guard-rspec" gem installed in开发者_如何学C my gemfile:

group :development do
  gem "guard-rspec"
  gem "growl"
end

When I run guard, it executes my rspec unit tests and outputs this message at the end:

Finished in 2.69 seconds
81 examples, 0 failures, 4 pending
/Users/KevinPang/.rvm/gems/ruby-1.9.2-p180/bin/rspec: No such file or directory - growlnotify --version

Note that if I actually type in that path in Terminal (/Users/KevinPang/.rvm/gems/ruby-1.9.2-p180/bin/rspec), it executes rspec:

/Users/KevinPang/.rvm/gems/ruby-1.9.2-p180/bin/rspec
No examples found.


Finished in 0.00003 seconds
0 examples, 0 failures

Figured it out. I forgot to install GrowlNotify.

Note: ensure that the versions of Growl and GrowlNotify are matching: