Shopify hosted payment gateway url callback

[ezechiel2019]

Using the shopify hosted payment gateway api , I keep receiving 422 unprocessable entity as i post (using query parameters ) the response to the callbackURL when i want to cancel the order. , what is missing ? i think my signature was right and the response payload is straight forward from what i see. Does the order has to be in a specific state in the management order dashboard before allow the cancel ?  Should we pass a json body or query parameters ? (or both ) ?

Thanks.

Sample of parameters :

"x_transaction_type": "authorization", "x_timestamp": "2020-55-22T14:07:289.055-14:289+0000", "x_signature": "ac752ef7e5ded8c19877d70e6c66ff2ce92dd508396ede6e3c15e8f6b296d96e", "x_reference": "13943250583601", "x_account_id": "SSSAAA-EDEDED-63E63224-9F25-45D5-9331-3388DA556BA6", "x_currency": "CAD", "x_amount": "19.56", "x_gateway_reference": "01f09dc92ee94c19a1f3bf782c16597d78292dcf-1595429659505-5-5-5-5-5", "x_result": "failed", "x_message": "CANCELING TRANSACTION", "x_test": "true" }