导航栏弹出菜单问题

Question

前台代码： 
<div class="nav">
        <div class="nale"><img src="images/datang/da01.jpg" width="6" height="40" /></div>
        <div class="namd">
         <ul class="naul"  id="nav">
            <li><a href="{$CATEGORY[93][url]}">{$CATEGORY[93][catname]}</a>
                <div class="ierj" style="left:-10px;">
                     <div class="jt" style="margin-left: 40px;"><img src="images/datang/in01.png" width="12" height="6" class="png"/> </div>
                     <div class="jixia">
                      <div style="margin-left:4px; float:left; display:inline;"><img src="images/datang/in04.png" width="7" height="35" class="png" /></div>
                        <div class="iecn">
                        <ul class="ieul">
                            {php $data1 = subcat("phpcms", 93);}
                            {php $c_count1 = count($data1);}
                            {loop $data1 $n $c}
                            {php $c_count1--;}
                                <li><a href="{$c[url]}" {if $c_count1==0}style="background:none;"{/if}>{$c[catname]}</a></li>
                            {/loop}
                        </ul>
                        </div>
                        <div class="turi"><img src="images/datang/in02.png" width="5" height="35" class="png" /></div>
                    </div>
                </div>
            </li>
          </ul>
       </div>样式表代码：
.nav{ width:1011px; height:auto;overflow: visible;position: absolute; z-index: 600;}
.nale{ float:left; display:inline;}
.namd{  display:inline; width:1002px; float:left;  background:url(../../../../images/datang/da02.jpg) repeat-x center bottom; height:auto; position: relative; overflow: visible;}
.naul{ float:left; display:inline;}
.naul li{ float:left; display:inline; font-size:12px; font-family:"微软雅黑"; margin:0px 15px; line-height:40px;height:auto;}
.naul li a{ color:#333; font-weight:bold;}
.naul li a:hover{ color:#004ea2; font-size:13px;}
.jt{ display:block; height:6px; width: 12px; padding: 0px;}
.jt img{ width: 12px; height:6px;float:left; display: inline; padding-right:100px;}
.ierj{ z-index:200;display:none; position:absolute; width:1002px; top:40px; height:101px;}
.ierj .iecn{ float:left; display:inline;}
.ierj .iecn{background: url(../../../../images/datang/in03.png); _filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled=true, sizingMethod=scale, src="../../../../images/datang/in03.png"); _background: none; height:35px;}
.ierj .ieul{ margin-left:5px;}
.ierj .ieul li{ height:35px; float:left; display:inline;text-align:left; margin:0px 5px; line-height:35px;}
.ierj .ieul li a{ font-size:12px; _position: relative; background:url(../../../../images/datang/in05.jpg) no-repeat right center; padding-right:10px;height:auto;}.turi{float: left; display:inline; width: 5px; height:35px;}
.jixia{ width: 1000px; display: block; height:35px; }
.naul li a:hover .ierj{
display:none;
}
.naul li a:hover .ierj{
display:block;
}
js代码：
function mainmenu(){
    if(isFirefox=navigator.userAgent.indexOf("Firefox")>0){    
$("#nav .ierj").css({display: "none"}); // Opera Fix
}
$("#nav li").hover(
function(){
$(this).find('.ierj:first').show();
},
        function(){
$(this).find('.ierj:first').hide();
});
} 
$(document).ready(function(){
mainmenu();
});
各位大虾们帮我看看这个样式为什么在ie6里边不管用，效果为鼠标移到栏目上 显示子栏目
谢谢