Background image not showing up with CSS

I created a simple GIF image of a very faint color gradient. The image size is 20x600 pixels. I set my CSS as follows:

body {
margin: 0;
font-family: Verdana, Arial, Helvetica, sans-serif;
font-size: 64%;
color: #000000;
background-image: url(..images/background.gif);
background-repeat: repeat-x; }

For some reason, I'm not seeing any changes. I even uploaded a test image of solid black (just in case I made the tint too light to see), and I still didn't see any changes.

Can anyone provide any pointers to get me back on track? I'm not sure if I have my codes are wrong, if there is a conflicting code somewhere, or if I was supposed to place a code in one of my template php files.

My test site is:
http://www.cobraplant.com/plants/

You seem to have a typo here:

background-image: url(..images/background.gif);

Should be:

background-image: url(../images/background.gif);

Thanks! That fixed the problem.