anyway to use a Nike voucher?

i did a trade with someone and it was for some shoes and a voucher. it was used a little bit of the balance. when i enter it in to check the balance it comes back as invalid and on NDC but when the original guy tries to use it, it comes up as valid... i even chatted with a nike rep and they confirmed it was valid.

anyone know whats going on? is it because it was already used to the persons address before?

you already know about nike vouchers and why you shouldnt be using them if they werent given to you by Nike.