Sometimes a voucher doesn't work if your order doesn't stick to the terms.
There may be a condition such as a minimum order value, an expiration date, a restriction on which products (discounted products such as packages are excluded) the voucher can be applied to, or a restriction on which customers (for example only new customers) can redeem it.
Please also check that you are actually placing your order at the foodspring online shop of your country. You will also need to manually enter the voucher code in the order overview at last, as it will not be deducted if you try to do so via link.
Also make sure that you enter the code correctly and do not accidentally mix up an "O" with a zero. As soon as you have entered the code, the discount will be displayed in the order overview.