I'm not getting any response on API

I'm not getting any response on API

I have this code

  1. private $token = '1234567890abcdefg';
  2. public $responseType = 'xml';
  4. public function getSearchRecordsByPDC($searchValue,$searchColumn='email')
  5. {
  6. $url = "https://crm.zoho.com/crm/private/".$this->responseType."/Leads/getSearchRecordsByPDC?newFormat=1&authtoken=".$this->token."&scope=crmapi&selectColumns=Leads(First Name,Lead Source,Phone,Mobile,Website,Lead Status,Description,Last Name,Website,Email,Lead Owner)&searchColumn=$searchColumn&searchValue=$searchValue";
  8. $result = $this->curlRequest($url);
  9. return $result;
  10. }

  12. public function curlRequest($url)
  13. {
  14. $ch = curl_init();
  15. curl_setopt($ch, CURLOPT_URL, $url);
  16. curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
  17. curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
  18. $output = curl_exec($ch);
  19. curl_close($ch);
  20. return $output;
  21. }

  23. $data = $zoho->getSearchRecordsByPDC('my_email@gmail.com');

  25. print_r($data);

I just simplified the code to not appear it to be very long. When running this code. I am not getting any response, even an error message or whatsoever, like I am getting a blank response, no xml response or whatever. But when ever I try to copy and paste the $url variable output into my web browser, I am getting response, and those response are valid.

What's wrong with this? Your help will be greatly appreciated! Thanks!