Fixed background iTheme2

I have recently set up a local installation of our wep pages but am having trouble getting the background image to stay fixed (so that it doesn’t scroll with the contents of the page).
In our old site (larvikok.wordpress.com) I found a setting for this and it worked. I have noticed that in the local installation (www.larvikok.no) I find no such setting. I have added “fixed” to this line in the Edit themes – Stylesheet CSS
/******
GENERAL STYLING
*****/
body {
background: #0d1424 url(images/body-bg.jpg) no-repeat left top fixed;
…
But it seems to have no effect on the way the page is showing.
Why are the two installations so different?