White page on openload when calling youtube-dl from php

[Medow]

Hello all:
I am trying to call download link from youtube-dl using php using this code:

<?php
$url = 'https://openload.co/embed/KxjGqMVBGag';
$cmd = 'youtube-dl --get-url ' . escapeshellarg($url);
echo exec($cmd);

But the result always return white page.
I try to change $url = 'https://openload.co/embed/KxjGqMVBGag'; to other hosts and thery are work perfect except for openload.
i can grab openload url when i excute the command from shell.

Please advice me.

Thanks.

[Medow]

@dstftw , why are you closing this?
I need to know the reason just for future case.