Gettext missing a method

After gem install gettext, I created the po/cs po/en po/de directories
and tried to create po files. But, with this code in rakefile

require ‘gettext/utils’
desc “Update pot/po files.”
task :updatepo do

GetText.update_pofiles(“semantickyweb2”,
Dir.glob("{app,lib,bin}/**/*.{rb,rhtml}"), “semantickyweb2 1.0.0”)
end

desc “Create mo-files”
task :makemo do
require ‘gettext/utils’
GetText.create_mofiles(true)

GetText.create_mofiles(true, “po”, “locale”) # This is for "Ruby on

Rails".
end

I got only this message:

Rake aborted!
Undefined method ‘untranslate_all?’ for Action::Class

Does somebody know what to do with that?

You probably didn’t add “require ‘gettext/rails’” in your Rails app.