Whenever adding or updating a tariff for any given product or country, please make certain to not only add the tariff, you'll next have to 

  1. Confirm this action [click button: "OK"], then 
  2. close the pop-up with the Zones/Tariffs [click button: "Sluiten"/"Fermer"/"Close"], and then 
  3. Save your configuration [click button: "Configuratie opslaan"/"Sauver la configuration"/"Save configuration"]

Please mind that, should you forget to save your configuration and switch to another screen or menu-item, then your changes will not be saved and, consequently, are lost. 

You then have no choice, but to to re-enter your configuration.



info on how to add countries/zones/tariffs can be found here and here.