Widget-Aware Problem

I manage a few websites using WordPress and this morning the side bars on one of them was gone and replaced with default theme text. When I checked in the dashboard it says my theme is not widget-aware. I use the headway theme on my sites and all the others are fine and don’t show this error. I’m hesitant to modify the functions.php when it is no different than on my other sites without this problem. I tried disabling all my plug-ins and the message still remains.

I would appreciate any advice on where to go from here.