[SOLVED] bakground image appears only in home page

Hi,
I use and image for my background in the layout area because it is semi transparent and it was the only way to see that background in Explorer.
Now I can see the background only in the home page, if you move to other pages there is not background:
http://prueba.karmeba.com/

if I put a color instead of an image in the background layout area it works ok in every page.

I really need some helop because I am not idea what's going on

Thanks in advance
Carme
xxx