Gamestop Certs not working.

I redeemed a few gamestop certificates and within 1 min walked in the store to use them for a game. However none of them would work or said the code was invalid. Does anyone have an idea why this may be?

I have a solution but you have to tell me who you buy from. Help me help you

I heard of an article where buying illegitimate GameStop points will be revoked from the account.