超级急小弟我的div如何不动了? _JavaScript

超级急...我的div怎么不动了????

<!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 id= "Head1 "> <title>
产品信息展示
</title>
<SCRIPT LANGUAGE= "JavaScript ">
var showad = true;
var Toppx = 100; //上端位置
var AdDivW = 30; //宽度
var AdDivH = 300; //高度
var PageWidth = 780; //页面多少宽度象素下正好不出现左右滚动条
var MinScreenW = 1024; //显示广告的最小屏幕宽度象素

function scall()
{
if(!showad)
{
return;
}
if (window.screen.width <MinScreenW)
{
showad = false;
document.getElementById( "Javascript.LeftDiv ").style.display= "none ";
document.getElementById( "Javascript.RightDiv ").style.display= "none ";
return;
}
var Borderpx = ((window.screen.width-PageWidth)/2-AdDivW)/2;

document.getElementById( "Javascript.LeftDiv ").style.display= " ";
document.getElementById( "Javascript.LeftDiv ").style.top=document.body.scrollTop+Toppx;
document.getElementById( "Javascript.LeftDiv ").style.left=document.body.scrollLeft+Borderpx;
document.getElementById( "Javascript.RightDiv ").style.display= " ";
document.getElementById( "Javascript.RightDiv ").style.top=document.body.scrollTop+Toppx;
document.getElementById( "Javascript.RightDiv ").style.left=document.body.scrollLeft+document.body.clientWidth-document.getElementById( "Javascript.RightDiv ").offsetWidth-Borderpx;
}

function hidead()
{
showad = false;
document.getElementById( "Javascript.LeftDiv ").style.display= "none ";