Theme css not finding images

Hi all,

i really can’t get out of this problem.

if i try this on my style.css:

.background {
background-image: url ('images/background.jpg');
}

it won’t load the image. this my folder hierarchy:

wordpress_folder/wp-contents/themes/my_theme/images/background.jpg

i’ve tried every path possible, ../ ‘ing till my root folder, but nothing.

in the html markup i know i should write

<img src="<?php bloginfo('template_directory')/images/background.jpg" />

and it works, but i cannot put php code in my css of course.
i tried to give a look to the default kubrick .css file, and i’ve noticed it just normally like this

.background {
background-image:url('images/background.jpg');
}

my folder hiersrchy is exactly the same, and the permissions seem to be tha same too.

anyone knows what i’m doing wrong? i’m loosing my day googling without finding a solution.