I'm getting Payment Not Completed right after CompleteMerchantValidation

I've verified my domain, made sure that what I'm sending in CompleteMerchantValidation is the correct response from Apple Server in a JSON format.

but whenever I run it, it executes CompleteMerchantValidation, pops the message Payment Not Complete, then session.onCancel is executed.

Any ideas why this could be happening?

I'm getting Payment Not Completed right after CompleteMerchantValidation
 
 
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