Trying to use an image background on .leftBoxHeading to no avail

[limelites]

I'm using the following code in my main stylesheet.css:

.rightBoxHeading, .leftBoxHeading {
background:transparent url(../images/button-bg.gif) repeat-x;
}

h3.rightBoxHeading, h3.leftBoxHeading {
background:transparent url(../images/button-bg.gif) repeat-x;

However, the button background just simply will not load! Where am I going wrong??