I don't now what to do
rubygems-0.9.4

=========================================================================== ====
/usr/lib/ruby/site_ruby/1.8/rubygems.rb:84:Warning: require_gem is
obsolete.  Use gem instead.
/usr/lib/ruby/site_ruby/1.8/rubygems.rb:76:in `active_gem_with_options':
undefined method `activate' for Gem:Module (NoMethodError)
        from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:61:in `require'
        from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:84
        from /var/lib/asterisk/agi-bin/comprobar-festivos.rb:17:in
`require'
        from /var/lib/asterisk/agi-bin/comprobar-festivos.rb:17
    -- AGI Script comprobar-festivos.rb completed, returning 0
=========================================================================== ======

In that case, use 'require <gemname>'
This is what the error message is telling you.

I have had problems with rubygems 0.9.4 and 0.9.3 on Windows.

My solution was to re-install Ruby which has rubygems 0.9.2, which
works fine.

My understanding is that it is install a prior version of rubygems
without having to re-install ruby.