can not redeem my gift card。

This link will take you to the section of the support article about what to do if it says your card is not valid --> If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support

Please review the support article that I’ve linked to below. It offers multiple solutions for the issue you’re experiencing. If none of the solutions work for you, please use the links in the article for contacting Apple support.

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support