I live in Trinidad and Tobago we bought our iPad and iTunes card in Miami when we are trying to redeem our card a message is coming up stating code must be redeemed in a US storefront

You won't be able to, all iTunes gift cards are country-specific, so to be able to redeem a US gift card you will need to be in the US with a US billing address and a US iTunes account. Do you know anybody in the US that you could give or sell the card to ?

This thread is 7 months old. To be able to redeem and use a US iTunes card you will need to be in the US with a US billing address on your account - you won't be able to change countries if you are using iTunes Match, have a balance on your account or have unexpired rentals or season passes.

I think you can change your country to the US store and it'll work then.