需要通过将参数传递给标头来获取服务器的响应

Question

I want response from an API by passing parameters to header. Here is what I had done:

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,"API url goes here");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS,$vars);  //Post Fields
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$headers = array();
$headers[] = 'auth_type:email';
$headers[] = 'user_name:testuser';
$headers[] = 'password:123456';
$headers[] = 'app_key:someapikey';
$headers[] = 'platform:platform name';
$headers[] = 'api_version: 1.0';

curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$server_output = curl_exec ($ch);

curl_close ($ch);

print  $server_output ;
?>

But Iam getting a blank page in response. Where Iam doing wrong?