flex-direction not being recognised by flexibility.js

[stelco]

Hi, I have built this CodePen where I am changing the column position using nth-child in CSS.

.athena .featured-wrap:nth-child(even) {
-js-flex-direction:row-reverse;
flex-direction:row-reverse;
}

This all works fine in all browsers apart from IE9 and below.
The issue appears to be flex-direction as this isnt being recognised by the flexibility script.
Here is a CodePen which you can open in Debug Mode in IE9. Any help on this appreciated. Thanks.

http://codepen.io/stelco74/pen/gLxVwO
or
http://s.codepen.io/stelco74/debug/gLxVwO