$ gem install yajl-ruby
Fetching: yajl-ruby-1.3.0.gem (100%)
Building native extensions. This could take a while...
Successfully installed yajl-ruby-1.3.0
Parsing documentation for yajl-ruby-1.3.0
Installing ri documentation for yajl-ruby-1.3.0
Done installing documentation for yajl-ruby after 0 seconds
1 gem installed
$ jekyll serve
/usr/share/rubygems/rubygems/dependency.rb:310:in `to_specs': Could not find 'yajl-ruby' (~> 1.2.0) - did find: [yajl-ruby-1.3.0] (Gem::MissingSpecVersionError)
Checked in 'GEM_PATH=/home/olea/.gem/ruby:/usr/share/gems:/usr/local/share/gems', execute `gem env` for more information
from /usr/share/rubygems/rubygems/specification.rb:1442:in `block in activate_dependencies'
from /usr/share/rubygems/rubygems/specification.rb:1431:in `each'
from /usr/share/rubygems/rubygems/specification.rb:1431:in `activate_dependencies'
from /usr/share/rubygems/rubygems/specification.rb:1413:in `activate'
from /usr/share/rubygems/rubygems/specification.rb:1445:in `block in activate_dependencies'
from /usr/share/rubygems/rubygems/specification.rb:1431:in `each'
from /usr/share/rubygems/rubygems/specification.rb:1431:in `activate_dependencies'
from /usr/share/rubygems/rubygems/specification.rb:1413:in `activate'
from /usr/share/rubygems/rubygems/core_ext/kernel_gem.rb:68:in `block in gem'
from /usr/share/rubygems/rubygems/core_ext/kernel_gem.rb:67:in `synchronize'
from /usr/share/rubygems/rubygems/core_ext/kernel_gem.rb:67:in `gem'
from /home/olea/bin/jekyll:22:in `<main>'
¿Qué hago mal?