background images for sidebox headings

I am trying to replace the sidebox headings background. I have followed the instructions indicated here:

http://www.zen-cart.com/content.php?173-can-i-use-an-image-for-the-sidebox-header

Right now my sidebox headings backgrounds in the stylesheet are:

h3.rightBoxHeading, h3.leftBoxHeading  {
background-color:#79A0BD;

I uploaded a box-title-bg.jpg image and changed the above in the stylesheet to be:

h3.rightBoxHeading, h3.leftBoxHeading  {
background:transparent url('../images/box-title-bg.jpg') center center no-repeat;

… and it does not work.
Do you know what I am doing wrong ?

I am using ZC 1.5: see a link to the site here: http://goo.gl/ylDnt

... please disregard. I have decided to use an image with text instead. This way I will be able to use a nice font as well. Thanks!