[API] currency_code error

Hi, I try to create transaction using api and send to .../transactions the following request;
{
        "type":"income",
        "account_id" : 12,
        "amount" : 34334,
        "currency_code": "EUR", 
        "currency_rate" : "0.80",
        "document_id" : 23,
        "contact_id" : 1,
        "category_id" : 22,
        "payment_method" : "offline-payments.cash.1"
}

in despite of using one of valid currency code I got this error;
422 Unprocessable Entity: [{"message":"The given data was invalid.","errors":{"currency_code":[" ge\u00e7ersiz bir d\u00f6viz kuru kodu."]}

can someone help me out to solve this issue?

I still couldn't find a solution, is there anyone who can help me :)