Why i can not pay by alipay

Normally Alipay should work. Our payment processing is done by Fastspring, a US-based eCommerce provider. You can contact them directly: https://fastspring.com/consumer-support-form/

They should be able to help you with all billing, invoice and tax questions.

But if they can not resolve the issue for any reason, please let us know. You can reach us at team AT a9t9.com