email not working no_from

Hi,

I use email library for my project. When I want to send an email, the debugger show this message : "lang:email_no_from"
My server use WAMP 3.1.0 and PHP 5.6.31.

My test code :

PHP Code:

$this->load->library('email');

$this->email->from('[email protected]');
$this->email->to('[email protected]');


$this->email->subject('Email Test');
$this->email->message('Hello World !');


$config['smtp_host']    = '172.20.2.2';
$config['smtp_port']    = '25';

$this->email->initialize();

if($this->email->send()){
            echo 'OK';
        }else{
            echo $this->email->print_debugger(); 


Do you know what this error means ?
Thanks,