Barkeep errors on unicorn.log

unicorn.log

/home/ravitezu/barkeep/barkeep_server.rb:142:in <class:BarkeepServer>': uninitialized constant BarkeepServer::AUTHENTICATION_PROTOCOL (NameError) from /home/ravitezu/barkeep/barkeep_server.rb:47:in'
from config.ru:2:in require' from config.ru:2:inblock in

'
from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/builder.rb:51:in instance_eval' from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/builder.rb:51:ininitialize'
from config.ru:1:in new' from config.ru:1:in'
from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.2.1/lib/unicorn.rb:44:in eval' from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.2.1/lib/unicorn.rb:44:inblock in builder'
from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.2.1/lib/unicorn/http_server.rb:694:in call' from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.2.1/lib/unicorn/http_server.rb:694:inbuild_app!'
from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.2.1/lib/unicorn/http_server.rb:136:in start' from /home/ravitezu/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.2.1/bin/unicorn:121:in'
from /home/ravitezu/.rbenv/versions/1.9.3-p194/bin/unicorn:23:in load' from /home/ravitezu/.rbenv/versions/1.9.3-p194/bin/unicorn:23:in'
I, [2015-06-03T17:50:12.402190 #11275] INFO -- : listening on addr=0.0.0.0:8040 fd=7
I, [2015-06-03T17:50:12.402522 #11275] INFO -- : Refreshing Gem list