Psn card does not work, what should I do although it was activated?

I got 20 euro psn credit today the problem is that the code is correct but the code is not accepted at the checkout the card was activated what can I do it says "add the 20 euro?" But when I click on the confirmation button it says "An error has occurred please try again" what can I do? The card was activated at the checkout

Do you still have the bill?

No, I have to rummage in the garbage to find this 😅