为什么我的phpMailer不能在localhost上工作？

My PHPMail is producing this error:

Message could not be sent.Mailer Error: SMTP connect() failed.

https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting..

  require 'PHPMailer/PHPMailerAutoload.php';

$mail = new PHPMailer;

//$mail->SMTPDebug = 3;                               // Enable verbose debug output

$mail->isSMTP();                                      // Set mailer to use SMTP
$mail->Host = 'smtp.gmail.com';  // Specify main and backup SMTP servers
$mail->SMTPAuth = true;                               // Enable SMTP authentication
$mail->Username = 'myorg@gmail.com';                 // SMTP username
$mail->Password = '******';                           // SMTP password
$mail->SMTPSecure = 'tls';                            // Enable TLS encryption, `ssl` also accepted
$mail->Port = 587;                                    // TCP port to connect to

$mail->setFrom('myorg@gmail.com', 'Kruze Zab');
$mail->addAddress('kruzezab@gmail.com', 'Kruze Zab');     // Add a recipient
                                                            // Name is optional
//$mail->addReplyTo('info@example.com', 'Information');
//$mail->addCC('cc@example.com');
//$mail->addBCC('bcc@example.com');

$mail->addAttachment('/var/tmp/file.tar.gz');         // Add attachments
$mail->addAttachment('/tmp/image.jpg', 'new.jpg');    // Optional name
$mail->isHTML(true);                                  // Set email format to HTML

$mail->Subject = 'Here is the subject';
$mail->Body    = 'This is the HTML message body <b>in bold!</b>';
$mail->AltBody = 'This is the body in plain text for non-HTML mail clients';

if(!$mail->send()) {
    echo 'Message could not be sent.';
    echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
    echo 'Message has been sent';
}

Here, I am trying to send an email through localhost but somehow its not allowing me. Any help appreciated