Из за чего возникает ошибка Internal server error при попытке отправить POST через CURL для оплаты частями от Privat Bank?

$curl = curl_init('https://payparts2.privatbank.ua/ipp/v2/payment/create');
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS,
    json_encode(array(
        'storeId' => '4AAD1369CF734B64B70F',
        'orderId' => '12211212121',
        'amount' => 2,
        'partsCount' => 5,
        'merchantType' => 'PP',
        'scheme' => 1111,
        'products' => array(
            array(
                'name' => 'test',
                'count' => 1,
                'price' => 2
            )
        ),
        'recipientId'=> 'qwerty1234',
        'responseUrl'=> 'https://adsasd',
        'redirectUrl'=> 'https://saddsa',
    'signature' => base64_encode ( SHA1 ( '75bef16bfdce4d0e9c0ad5a19b9940df'.'4AAD1369CF734B64B70F'.'12211212121'.' 200'.' 5'.' PP'.'https://adsasd'.'https://saddsa'.' test1200'.' 75bef16bfdce4d0e9c0ad5a19b9940df' ))
    ))
);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_HEADER, 0);
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Accept: application/json','Accept-Encoding: UTF-8','Content-Type: application/json; charset=UTF-8'));
curl_setopt($curl, CURLOPT_TIMEOUT, 30);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
//execute curl
$response = curl_exec($curl);

//get execute result
$curl_errno = curl_errno($curl);
$curl_error = curl_error($curl);
$aInfo = @curl_getinfo($curl);
//close curl
curl_close($curl);



$response =  json_decode($response,true);
print_r($response);