What Am I Doing Wrong???? I Cannot Get It To Work!

Hiya,

I am really looking forward to getting this working, however, cannot work out what is wrong!

I have a test site http://nelsonevents.co.uk/ne2013/, using U-Design theme, and am sute I have set it up properly, but cannot get the background to change!

What am I doing wrong??

http://wordpress.org/extend/plugins/background-manager/