could not send the notification using topic messaging - php

Question

could not send the notification using topic messaging. Here i am attached the code. Please check it. it runs fine on the postman. But could not get the notification.
$topic = $_POST['topic'];
$headers = [
'Authorization: key=' . API_ACCESS_KEY,
'Content-Type: application/json'
];
if($_POST['send_to']=='topic'){
$fcmNotification = array(
'to' => '/topics/'.$topic,
'notification' => $dataToSentNotification,
);
}
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$fcmUrl);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fcmNotification));
$results = curl_exec($ch);
curl_close($ch);

Answer 1

Use the curl_errno function to get the specific error, code as follow:
$error_msg = NULL;
if (curl_errno($ch)) {
$error_msg = curl_error($ch);
}
curl_close($ch);
if ($error_msg !== NULL) {
print_r($error_msg);
}
As aynber says, add the whole curl sentences inside if or what do you expect if $fcmNotification is empty or null?