问题：
1、为什么naviga_bgimg下的li无法实现图片轮播？
2、为什么鼠标移入naviga_icons中的图标后无法切换对应的背景图片？
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title> new rollimg </title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<script type="text/javascript" src="scripts/js/jquery-1.4.1.js"></script>
</head>
<body>
<style type="text/css">
* { margin:0px; padding:0px; }
#naviga_bgimg { width:900px; height:330px; position:absolute; background:#fff center center no-repeat; }
#naviga_bgimg ul li { float:left; list-style:none; position:absolute; }
#naviga_icons { position:absolute; padding-left:30px; width:870px; height:180px; top:150px; background:url("image/nav_bg.png") bottom left repeat-x; }
#naviga_icons a { display:inline-block; width:100px; height:180px; background:url("image/icoNav_n01.png") bottom center no-repeat; }
#naviga_icons a.icon2 { background-image:url("image/icoNav_n02.png"); }
#naviga_icons a.icon3 { background-image:url("image/icoNav_n03.png"); }
#naviga_icons a.icon4 { background-image:url("image/icoNav_n04.png"); }
#naviga_icons a.icon5 { background-image:url("image/icoNav_n05.png"); }
#naviga_icons a.icon6 { background-image:url("image/icoNav_n06.png"); }
#naviga_icons a.icon1:hover { background-image:url("image/icoNav_c01.png"); }
#naviga_icons a.icon2:hover { background-image:url("image/icoNav_c02.png"); }
#naviga_icons a.icon3:hover { background-image:url("image/icoNav_c03.png"); }
#naviga_icons a.icon4:hover { background-image:url("image/icoNav_c04.png"); }
#naviga_icons a.icon5:hover { background-image:url("image/icoNav_c05.png"); }
#naviga_icons a.icon6:hover { background-image:url("image/icoNav_c06.png"); }
</style>
<script type="text/javascript">
var nav_time = "";
var nav_index = 1;
var $icolist=$("#naviga_icons a");
var $imglist=$("#naviga_bgimg ul li");
var nav_count=$icolist.length;
$(function() {
navShow(nav_index);
//鼠标移入移出
$icolist.hover(function () {
clearTimeout(nav_time);
var nav_icon=$icolist.index($(this));
$imglist.hide().stop(true,true).eq(nav_icon-1).fadeIn("slow");
}, function () {
var nav_icon=$icolist.index($(this));
nav_index=nav_icon > nav_count ? 1 :parseInt(nav_icon)+1;
nav_time = setTimeout("navShow(" + nav_index + ")", 4000);
});
});
function navShow(num) {
nav_index = num;
$imglist.hide().stop(true,true).eq(nav_index-1).fadeIn("slow");
nav_index = nav_index + 1 > nav_count ? 1 : nav_index + 1;
nav_time = setTimeout("navShow(" + nav_index + ")", 4000);
}
</script>
<div id="naviga">
<div id="naviga_bgimg">
<ul>
<li><img src="image/navbg_01.jpg" /></li>
<li><img src="image/navbg_02.jpg" /></li>
<li><img src="image/navbg_03.jpg" /></li>
<li><img src="image/navbg_04.jpg" /></li>
<li><img src="image/navbg_05.jpg" /></li>
<li><img src="image/navbg_06.jpg" /></li>
</ul>
</div>
<div id="naviga_icons">
<a class="icon1" href="#"></a>
<a class="icon2" href="#"></a>
<a class="icon3" href="#"></a>
<a class="icon4" href="#"></a>
<a class="icon5" href="#"></a>
<a class="icon6" href="#"></a>
</div>
</div>
</body>
</html>
