Installing ruby gem from git repository failed: rake aborted -

i cloned git repository local machine cant install gem.. (i installed rake 10.1.0), dependent gem oauth installed

    git clone git://github.com/marcel/twurl.git     rake gem --trace 

error message:

rake aborted! don't know how build task 'gem' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/task_manager.rb:49:in `[]' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:148:in `invoke_task' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:106:in `top_level' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:106:in `each' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:106:in `top_level' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:115:in `run_with_threads' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:100:in `top_level' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:78:in `run' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling' /library/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:75:in `run' /library/ruby/gems/1.8/gems/rake-10.1.0/bin/rake:33 /usr/bin/rake:19:in `load' /usr/bin/rake:19 

i appreciate help!

use

gem build twurl.gemspec 

instead of

rake gem 

the error message states, rakefile has no task named gem.

after have gem built, install gem install.