background images in css

[eluser]Unknown[/eluser]
hi guys, i have searched this forums and found some threads that may help me in this but still it dont work in me.

i just want to have a background image for my header.and it has code like this,.

Code:

<div class="container_12 header_back2">

<hr/>
<div class="grid_8 header_style">Makiling Biodiversity Information System</div>
<div class="grid_1 header_link_style">&lt;?php echo anchor('user/admin_home','Home');?&gt;</div>
<div class="grid_1 header_link_style">about</div>
<div class="grid_1 header_link_style">&lt;?php echo anchor('user/admin_logout','Logout');?</div>

</div>

my css file is inside a folder "design" and the image i want to load is inside the folder "images" inside the "design" folder.
note: design folder is in the same level of systems and application folders. CI version 2.0.3

styles.css

Code:

header_back2{
padding:0px;
margin:0px;
background: url(images/body-bg.png) 0 0 repeat-x;  
}

the image dont load..T_T pls help me or correct me if i am wrong in this implementation.
thank you in advance.
mark.d