Transaction start was failed!API REQUEST
Array
(
    [salt] => f7efcc56a1a3f22b17e4ec088c216c71
    [merchant] => 
    [orderRef] => 12700116117447409027
    [currency] => HUF
    [sdkVersion] => SimplePay_PHP_SDK_2.1.0_200825:c8f0c15958c8bc6f37ade6563296dcbf
    [methods] => Array
        (
            [0] => CARD
        )

    [total] => 25
    [threeDSReqAuthMethod] => 02
    [customerEmail] => sdk_test@otpmobil.com
    [language] => HU
    [timeout] => 2021-01-27T11:02:20+00:00
    [url] => http://sura-motors.ravon.ru/back.php
    [invoice] => Array
        (
            [name] => SimplePay V2 Tester
            [country] => hu
            [state] => Budapest
            [city] => Budapest
            [zip] => 1111
            [address] => Address 1
        )

)
API RESULT
Array
(
    [responseBody] => {"errorCodes":[5201],"salt":"TVgBZ3veWs03g7rkYWEP6UgibiyVAT8g","total":0.0}
    [responseSignature] => MISSING_HEADER_SIGNATURE
    [responseSignatureValid] => 
    [errorCodes] => Array
        (
            [0] => 5201
        )

    [salt] => TVgBZ3veWs03g7rkYWEP6UgibiyVAT8g
    [total] => 0
    [form] => Transaction start was failed!
)