Twenty Eleven Theme

Hello,

I am attempting to follow directions at http://twentyelevendemo.wordpress.com/2011/05/04/featured-posts-in-twenty-eleven/
Featured Posts in Twenty Eleven
“…If you add a Featured Image the same size as the Custom Header Image it’ll be used as a full-width image link to the post…”

However, I am using a 1000×288 png which IS the same width as the Header Image (in fact I took one of the sample header images and modified it).
But I just can’t seem to get it to display as a full width image?!!! Argh. It always gets resized and displayed on the side.

My site is http://www.avising.com
Here is the image I am using: you can check yourself it is 1000×288.
http://www.avising.com/wp-content/uploads/2014/08/FeaturedImage9_1000x288.png

The look I am trying to emulate is on page
http://twentyelevendemo.wordpress.com/showcase/ (click to advance to second featured post)
See screenshot at http://www.avising.com/wp-content/uploads/2014/09/Example.png

Please help.
-Avi