Following on from my recent query about Preferential tariffs, my supplier in the EU now has a REX number and as far as I can see, our imports of sails are now having the correct preferential tariff (0%) applied. We've previously paid the 3rd country rate of 12% on a number of imports. I understand that I can claim repayment of the duty paid on these - I am trying to enter claims on the website, but as soon as I enter the MRN, I get a message "Sorry, there is a problem with this MRN The MRN xxxxxxxxxxxxxxxxxx is invalid or there’s no duty or VAT in this MRN to claim." The MRN relates to a shipment that we paid £1477.55 duty on. The shipment in question contained 3 Sails - HS code is 63063000 - Sails. These were declared as having Preferential origin of Croatia, hence should have attracted duty of 0% under the TCA if the proper declaration was made. Due to the missing REX no, we were charged 12%. This was handled by the couriers - I can't see the declaration in our CDS dashboard. I am sure that I am doing something wrong, but I don't know what! Can anyone advise where I am going wrong?