Need help with multiple author boxes

I have tried entering the short code suggested to get multiple author boxes to show up on one post, but it’s not working. Please advise. Thank you!

You can use startbox shortcode at the bottom of the content like this: [starbox id=”john,david”] where john and david are the username of the authors or [starbox id=”1,2..n”] where 1,2, .. n are the ID of the authors