i'm using following javascript for 2 level menu. it's working fine in IE but on mouseover showing javascript error 'submenuobject.filters.alpha is null or not an object'.
In mozilla on mouseover submenu is not at all appearing.
i searched a lot,did all tricks but no use.can anyone help me?please.



var mastertabvar=new Object()
mastertabvar.baseopacity=0
mastertabvar.browserdetect=""

function showsubmenu(masterid, id){
if (typeof highlighting!="undefined")
clearInterval(highlighting)
submenuobject=document.getElementById(id)
mastertabvar.browserdetect=submenuobject.filters? "ie" : typeof submenuobject.style.MozOpacity=="string"? "mozilla" : ""
hidesubmenus(mastertabvar[masterid])
submenuobject.style.display="block"
instantset(mastertabvar.baseopacity)
highlighting=setInterval("gradualfade(submenuobject)",50)
}

function hidesubmenus(submenuarray){
for (var i=0; i<submenuarray.length; i++)
document.getElementById(submenuarray[i]).style.display="none"
}

function instantset(degree){
if (mastertabvar.browserdetect=="mozilla")
submenuobject.style.MozOpacity=(degree/100)
else if (mastertabvar.browserdetect=="ie")
submenuobject.filters.alpha.opacity=degree
}


function gradualfade(cur2){
if (mastertabvar.browserdetect=="mozilla" && cur2.style.MozOpacity<1)
cur2.style.MozOpacity=Math.min(parseFloat(cur2.style.MozOpacity)+0.1, 0.99)
else if (mastertabvar.browserdetect=="ie" && cur2.filters.alpha.opacity<100)
cur2.filters.alpha.opacity+=10
else if (typeof highlighting!="undefined") //fading animation over
clearInterval(highlighting)
}

function initalizetab(tabid){
mastertabvar[tabid]=new Array()
var menuitems=document.getElementById(tabid).getElementsByTagName("li")
for (var i=0; i<menuitems.length; i++){
if (menuitems[i].getAttribute("rel")){
menuitems[i].setAttribute("rev", tabid) //associate this submenu with main tab
mastertabvar[tabid][mastertabvar[tabid].length]=menuitems[i].getAttribute("rel") //store ids of submenus of tab menu
if (menuitems[i].className=="selected")
showsubmenu(tabid, menuitems[i].getAttribute("rel"))
menuitems[i].getElementsByTagName("a")[0].onmouseover=function(){
showsubmenu(this.parentNode.getAttribute("rev"), this.parentNode.getAttribute("rel"))
}
}
}
}