Bundle install not working

[awlad]

gem 'nkss-rails', github: 'nadarei/nkss-rails', branch: 'master' or gem 'nkss-rails','0.0.2', github: 'nadarei/nkss-rails'

In rails 4.2.8

Bundle install giving me: An error occurred while installing nkss-rails (0.0.2), and Bundler cannot continue.

Log:

NoMethodError: undefined method spec' for nil:NilClass
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/2.4.0/rubygems/installer.rb:262:in spec' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/2.4.0/rubygems/installer.rb:762:in build_extensions'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/source/path.rb:188:in generate_bin' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/source/git.rb:166:in install'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/installer.rb:104:in block in install_gem_from_spec' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/rubygems_integration.rb:162:in with_build_args'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/installer.rb:103:in install_gem_from_spec' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/installer.rb:264:in block in install_sequentially'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/2.4.0/forwardable.rb:229:in each' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/2.4.0/forwardable.rb:229:in each'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/installer.rb:263:in install_sequentially' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/installer.rb:90:in run'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/installer.rb:18:in install' /home/vagrant/.rbenv/rbenv.d/exec/gem-rehash/rubygems_plugin.rb:27:in install'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/cli/install.rb:79:in run' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/cli.rb:145:in install'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/vendor/thor/command.rb:27:in run' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/vendor/thor/invocation.rb:121:in invoke_command'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/vendor/thor.rb:363:in dispatch' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/vendor/thor/base.rb:440:in start'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/cli.rb:9:in start' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/bin/bundle:20:in block in <top (required)>'
/home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/lib/bundler/friendly_errors.rb:5:in with_friendly_errors' /home/vagrant/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/bundler-1.7.4/bin/bundle:18:in <top (required)>'
/home/vagrant/.rbenv/versions/2.4.4/bin/bundle:23:in load' /home/vagrant/.rbenv/versions/2.4.4/bin/bundle:23:in

'
An error occurred while installing nkss-rails (0.0.2), and Bundler cannot continue.
`