422 on payment submission using checkout API

[Aar]

Hello, when I use the checkout API to submit my payment, I get 422 response saying:

{"errors":{"credit_card":[{"code":"invalid","message":"is invalid","options":{}}]}}

"x-request-id":"3f4e4177-7320-4ec5-ad5a-145d9f92f722",

I should also mention the store is in test mode, I am using the card 4242424242424242 to checkout.

This is via sending

                    "payment": {
                        "request_details": {
                            "ip_address": "166.1.139.165",
                            "accept_language": "en-US",
                            "user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.98 Safari/537.36"
                        },
                        "amount": this.checkoutTotal,
                        "session_id": this.vaultToken,
                        "unique_token": this.idempotencyToken
                    }