In case u receive this error with such explanation:

translation data can not be used with :count => 2

Remember that you need to define a “few” and “many” key for translation for particular entity, e.g.:

pl:
  activerecord:
    models:
      article:
        one: “Artykuł”
        few: “Artykuły”
        many: “Artykułów”
        other: “Artykuły”