Form fails to send when using invalid email domain (no error message)

During testing when I submit a form with an invalid email domain the form fails to send and doesn’t display an error message. In the "default.inc.php" file I can see among the other error messages this one:

$_lang[’formit.email_invalid_domain’] = ’Your email address does not have a valid domain name.’;

Does anyone know how to get this working?


formit 1.5.4
revo 2.0.7-pl