document.all.chip1.style 为空或不是对象

代码如下：总提示报错，请教原因

<script LANGUAGE="JavaScript">
var brOK=false;
var mie=false;
var aver=parseInt(navigator.appVersion.substring(0,1));
var aname=navigator.appName;
function checkbrOK()
{if(aname.indexOf("Internet Explorer")!=-1)
{if(aver>=4) brOK=navigator.javaEnabled();
mie=true;
}
if(aname.indexOf("Netscape")!=-1)
{if(aver>=4) brOK=navigator.javaEnabled();}
}
var vmin=2;
var vmax=5;
var vr=0.02;
var timer1;
function Chip(chipname,width,height)
{this.named=chipname;
this.vx=vmin+vmax*Math.random();
this.vy=vmin+vmax*Math.random();
this.w=width;
this.h=height;
this.xx=0;
this.yy=0;
this.timer1=null;
}
function movechip(chipname)
{
if(brOK)
{eval("chip="+chipname);
if(!mie)
{pageX=window.pageXOffset;
pageW=window.innerWidth;