Hello, I have a question about my sony z500a

Posted by taz0x
I read the instruction book about being able to read text messages with the external display while the clamshell is closed by pressing the + volume button. now whenever I get a text message, i try to read it using that method, but pressing the + button never did anything (not even holding down the button didn't do anything), and after a bunch of tries, all it does is nothing when there is an alert for new messages, and when I press the + button it just displays the phone status on the external display (like the profile, free space), so i'm wondering, how DO YOU read text messages on the external display like it states on the instruction book.