background image shows in FF3, not IE7

I have an image which I am displaying in my primary links navigation bar across the top of my site. It shows up fine in FF3, but not at all in IE7. Note the line "background:url(icons/menu.png) no-repeat;" in the following code, which is the image i am displaying. I also tried using .gif but it did not work either. It's a 75x25px image I created in Paint.NET. Any idea how I can get this to show in IE? Thanks, Bill

(Framework Theme) style.css:

ul.links li {
background: none;
margin: 0 10px 0 0;
padding: 0;
}

#nav {
border-bottom: 1px solid #000066; /* was b4d7f0 (same for next line */
border-top: 1px solid #000066;
font-size: 1em;
margin: 0 0 10px;
}

#nav ul.primary-links {
padding-left: 90px; /* wasnt here before */
padding-top: 5px; /* wasnt here before */
padding-bottom: 5px; /* wasnt here before */
background-position: center left; /* wasnt here before */
background:url(icons/artists-menu.png) no-repeat; /* background: #ffffff; */ /* was #d4e7f3 */
float: center;
font-weight: 700;
/* padding: 5px; */
}

#nav ul.primary-links li {
margin: 0;
padding: 0;
}

#nav ul.primary-links li a:link {
margin: 0 10px 0 0;
padding: 5px 0;
color: #ff0033;
}

#nav ul.primary-links li a:visited {
margin: 0 10px 0 0;
padding: 5px 0;
color: red;
}

#nav ul.primary-links li a:hover, #nav ul.primary-links li a:active {
text-decoration: underline;
}