Zoho Not Working With Phpmailer on Server but working on local

Hello

To send mail i used phpmailer with zoho , perfectly working on local environment but not working on server. gives me error coundn't authenticate.

$mail->Host = 'ssl://smtp.zoho.com'; // Specify main and backup SMTP servers

$mail->SMTPAuth = true; // Enable SMTP authentication

$mail->Username = 'my email id of zoho'; // SMTP username

$mail->Password = 'password of zoho'; // SMTP password

$mail->SMTPSecure = 'tls'; // Enable TLS encryption, `ssl` also accepted

$mail->Port = 587;

$mail->setFrom('mail-alias ', 'sitename');