The problem might be the same one I had when I first attempted posting pictures. I was pasting the web page URL; you need to post the picture's URL. Right click on the picture; click on properties; cut and paste the address URL. Here's what I get on the page you chose.
This is the URL address I'm using:http://www.johnbaeder.com/Oils/400x/400xWhite-Manna-Hamburgers-.jpg
As I posted this it added an underline that was not on the original URL but hope this helps. Keep trying. Some one helped me out this very same way and my original attempts gave me that very same X'd out box you are getting.
By the way, I love his pictures of those diners; great stuff!