Flysystem SFTP connection

Hi,

I've tried to save my data cross domain but in the same server using flysystem by campbell. https://github.com/GrahamCampbell/Laravel-Flysystem

But i cannot make it work using SFTP. Here is the error:

   Could not login with username: forge

Even i'm specift the privateKey but its not working. Here is my current setup:

   'sftp'      => [
        'driver'     => 'sftp',
        'host'       => 'xxxx.xxx.xxxx',
        'port'       => 22,
        'username'   => 'forge',
        'password'   => 'xxxxxxxxx',
        'privateKey' => '~/putty/privateKey.ppk',
        'root'       => 'cdn.example.com/public',
        'timeout'    => 10
    ],

Is there any other setup for using flysystem that i miss or is there any better way to save uploaded file to another domain? i already install

   "league/flysystem-sftp": "~1.0"

Edit: I'm using laravel forge for the server handling.

Thanks