Emails not sent when Private post is updated

Hi

The email notifications are working well for updating a public post and changing a public post to private, but when I update the private post there is no notification. I see you have the following line in bnfw.php (line 137):

add_action( ‘publish_to_publish’ , array( $this, ‘update_post’ ) );

Is it possible to add the following, or is there a better way to do it?

add_action( ‘private_to_private’ , array( $this, ‘update_post’ ) );

Many thanks

Liz