Create a refund programmatically

Hi to all,
I want to create a refund programmatically, so I use wc_create_refund(), but it returns me “An error occurred while attempting to create the refund using the payment gateway API.”.
So I flow the code to find where this message come from. The massage is from same file where wc_create_refund() is, and the function is wc_refund_payment().

In this function we have the following few lines of code:

$result = $gateway->process_refund( $order->get_id(), $amount, $reason );

if ( ! $result ) {
throw new Exception( __( ‘An error occurred while attempting to create the refund using the payment gateway API.’, ‘woocommerce’ ) );
}

Following the code again I found process_refund() function in the abstract class WC_Payment_Gateway. But this function always return false:

public function process_refund( $order_id, $amount = null, $reason = ” ) {

return false;
}

so I can not see the way I can skip this check if ( ! $result ).

Can someone help me? Do I use the correct functions or there is another solution to create refund?

Regards!