Transaction start was failed!API REQUEST
Array
(
    [salt] => 352782ee580948f4af8f2513529277da
    [merchant] => 
    [orderRef] => 12700116108828743202
    [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] => 2021-01-17T11:37:54+00:00
    [url] => http://prevox.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":"36mujVHWU7wHVPn5zojcuhByoN0ygGzy","total":0.0}
    [responseSignature] => MISSING_HEADER_SIGNATURE
    [responseSignatureValid] => 
    [errorCodes] => Array
        (
            [0] => 5201
        )

    [salt] => 36mujVHWU7wHVPn5zojcuhByoN0ygGzy
    [total] => 0
    [form] => Transaction start was failed!
)