ruby on rails - Why do I get this Fedena installation error? -

i wanted install fedena on cpanel, when used command rake gems:unpack got error:

fedena requires i18n gem version 0.4.0 installed. run gem install i18n -v 0.4.0 rake aborted! error: 'rake/rdoctask' obsolete , no longer supported. use 'rdoc/task' (available in rdoc 2.4.2+) instead. /home/iiumprin/public_html/projectfedena-fedena-84b5ad9/rakefile:8 (see full trace running task --trace) 

i have i18n gem inside ruby it's still giving me error, should do?

'rake gems:unpack --trace'

iiumprin@iiumprinting.com [~/public_html/projectfedena-fedena-84b5ad9]# rake gems:unpack --trace fedena requires i18n gem version 0.4.0 installed.run gem install i18n -v 0.4.0 rake aborted! error: 'rake/rdoctask' obsolete , no longer supported. use 'rdoc/task' (available in rdoc 2.4.2+) instead. /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/rdoctask.rb:2 /usr/lib/ruby/site_ruby/1.8/rubygems/core_ext/kernel_require.rb:45:in `gem_original_require' /usr/lib/ruby/site_ruby/1.8/rubygems/core_ext/kernel_require.rb:45:in `require' /home/iiumprin/public_html/projectfedena-fedena-84b5ad9/rakefile:8 /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/rake_module.rb:25:in `load' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/rake_module.rb:25:in `load_rakefile' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:637:in `raw_load_rakefile' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:94:in `load_rakefile' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:93:in `load_rakefile' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:77:in `run' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/lib/rake/application.rb:75:in `run' /usr/lib/ruby/gems/1.8/gems/rake-10.1.0/bin/rake:33 /usr/bin/rake:23:in `load' /usr/bin/rake:23