PayPal DoDirectPayment working without cvv - php

Question

Hi I implement PayPal DoDirectPayment in my website, I want to required expire date And CVV but payment taking without those with this warning "This transaction was approved. However, the Card Security Code provided had too few, too many, or invalid character types but, as per your account option settings, was not required in the approval process"
I'm using PHP.
My Code is
$api_endpoint = 'https://api-3t.sandbox.paypal.com/nvp';
$request = array
(
'METHOD' => 'DoDirectPayment',
'USER' => 'sell3_api1.pay.com',
'PWD' => '75DQHCABLDFSDF',
'SIGNATURE' => 'AFcWxV21C7fd0asdasdCpasdsdAtxzafSFsaKZ3unSUBjX9r-',
'VERSION' => '55.0',
'PAYMENTACTION' => 'Sale',
'FIRSTNAME' => $current_user->user_login,
'LASTNAME' => '.',
'IPADDRESS' => $_SERVER['REMOTE_ADDR'],
'ACCT' => $acct,
'CREDITCARDTYPE'=>
'EXPDATE' => $month.$year,
'CVV2' => $cvv,
'AMT' => $amt,
'CURRENCYCODE' => 'USD',
);
$nvp_string = '';
foreach ($request as $key => $value) {
$nvp_string .= '&'.$key.'='.urlencode($value);
}
$curl = curl_init();
curl_setopt($curl, CURLOPT_VERBOSE, 1);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($curl, CURLOPT_TIMEOUT, 30);
curl_setopt($curl, CURLOPT_URL, $api_endpoint);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_POSTFIELDS, $nvp_string);
$result = curl_exec($curl);
curl_close($curl);
parse_str($result);
How can I solve It.