Far Cry 3 not recognizing 21:9 resolution?

[mclarenf1god]

Hello. I've got a quick question for all of you.

I'm playing on a Dell Ultrasharp U2913WM display at 2560 x 1080. Despite selecting this resolution from the game menu, the image is still displayed at 1920 x 1080, with black bars on the side.

I found this older WSGF post, but am not sure why I am not getting the same result.

http://www.wsgf.org/forums/viewtopic.php?f=68&t=25077&view=print

Thanks.