Background:none doesn't work (in IE)

Something as simple as "background: none;" when placing a "like" item within another doesn't work in IE7 OR IE6.

<ul id="mainNav" style="">

<li style="" class="group1"><a href="#" onmousedown="showhide('mainSubGroup1')">Energy &amp; Resource Management</a>

<ul id="mainSubGroup1">

<li id="s-t01"><a href="#" style="">Environmental Stewardship</a></li>

<li id="s-t02"><a href="/energy/index.php" style="">Climate Savers Computing Initiative</a></li>

<li id="s-t03"><a href="#" style="">Parking and Transportation Services</a></li>

<li id="s-t04"><a href="#" style="">Utilities and Plant Engineering</a></li>



</ul>

</li>



IF there is a background of some sort on the first <li> item, the items in the next level will use them as well. Adding "background:none;" does not work. Must replace with something.