Q: I can not redeem my iTunes card. Should be in US storefront.

You can't, all iTunes gift cards are country-specific, they can only be redeemed and used in their country of issue - so if it's a US card then you will need to be in the US with a US billing address. Do you know anybody in the US that you could sell or give the card to ?

But I'm in america and still it doesn't redeem

You are in the US, you have your US billing address on your iTunes account, and you've tried logging out and back into your account on the device/computer that you are using ?