Admin Forum:Changing the background of my wiki

I changed the background of my wiki using the theme editor:

http://he.elect.wikia.com/wiki/%D7%A2%D7%9E%D7%95%D7%93_%D7%A8%D7%90%D7%A9%D7%99

I selected an image as a background.

But, I cannot see the background I selected - I still see white background!