js滚动条在弹出框中异常问题

有一段js代码。带横向滚动条的多张图片展示
写在单独页面里面，功能正常
但是写在弹出框中，滚动条无法滚动。
请教大家原因。js代码
<!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><style>
body,div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,form,fieldset,input,p,blockquote,th,td{margin:0;padding:0;font-size:12px}
table{border-collapse:collapse;border-spacing:0;}
fieldset,img{border:0;}
address,caption,cite,code,dfn,em,strong,th,var{font-style:normal;font-weight:normal;}
ol,ul {list-style:none;}
caption,th {text-align:left;}
h1,h2,h3,h4,h5,h6{font-size:100%;}
body{ font:12px/160% "宋体"}
#picBox{width:880px; height:100px; border:#ccc solid 1px; margin:10px auto; padding:10px; overflow:hidden; position:relative;}
#picBox ul{overflow:hidden;position:absolute; top:10px; left:0;}
#picBox li{ float:left; width:225px; height:100px; line-height:100px; text-align:center;}
#picBox li a{ display:block; width:200px; height:100%; margin:0 auto;text-align:center; background:#FF9900;}
#scrollBar{ width:900px; height:20px; border:#ccc solid 1px; margin:0 auto}
#scrollBar #dragObj{ width:100px; height:20px; text-align:center; cursor:pointer; background:#DDD}
</style>
</head>
<body>
<div id="picBox">
<ul id="picList">
<li><a href="#">图片地址1</a></li>
<li><a href="#">图片地址2</a></li>
<li><a href="#">图片地址3</a></li>
<li><a href="#">图片地址4</a></li>
<li><a href="#">图片地址5</a></li>
<li><a href="#">图片地址6</a></li>
<li><a href="#">图片地址7</a></li>
<li><a href="#">图片地址8</a></li>
<li><a href="#">图片地址9</a></li>
<li><a href="#">图片地址10</a></li>
</ul>
</div><div id="scrollBar"><div id="dragObj">拖动</div></div>
<script type="text/javascript">
(function(){
if(!window.zzc){window['zzc'] = {} };
function isIE(){ return (document.all) ? true : false;};
window['zzc']['isIE'] = isIE;
function $(id){return typeof id == 'string' ? document.getElementById(id) : id};
window['zzc']['$'] = $;
function $$(id,tag){return $(id).getElementsByTagName(tag);}
window['zzc']['$$'] = $$;
function getElementsByClassName(name,type){
var r=[];
var re=new RegExp("(^|\\s)"+name+"(\\s|$)");
var elem=document.getElementsByTagName(type||"*");
for(var i=0;i<elem.length;i++){
if(re.test(elem[i].className)) r.push(elem[i]);
}
return r;
}
window['zzc']['getElementsByClassName'] = getElementsByClassName;
function addEvent(eventTarget,eventType,fnHandler){
 if(eventTarget.addEventListener){//for FF
eventTarget.addEventListener (eventType,fnHandler,false);
 } else if(eventTarget.attachEvent){//for IE
eventTarget.attachEvent("on" + eventType,fnHandler);
 } else{//for other
eventTarget["on" + eventType] = fnHandler;
 }
     };
window['zzc']['addEvent'] = addEvent;
function removeEvent(eventTarget,eventType,fnHandler){
 if(eventTarget.removeEventListener){//for FF
eventTarget.removeEventListener (eventType,fnHandler,false);
 } else if(eventTarget.detachEvent){//for IE
eventTarget.detachEvent("on" + eventType,fnHandler);
 } else{//for other
eventTarget["on" + eventType] = null;
 }
     };
window['zzc']['removeEvent'] = removeEvent;
function getBrowerWindowSize(){
    var de = document.documentElement;
    return{ 
'width':(self.innerWidth||( de && de.offsetWidth )||document.body.offsetWidth),
'height':(self.innerHeight||(de && de.offsetHeight)||document.body.offsetHeight)
}
};
window['zzc']['getBrowerWindowSize'] = getBrowerWindowSize;
function getPageSize(){
var de=document.documentElement;
return{
'width':(document.body.scrollWidth||(de&&de.scrollWidth)),
'height':(document.body.scrollHeight||(de&&de.scrollHeight))
}
};
window['zzc']['getPageSize'] = getPageSize;
function pageX(elem){
return elem.offsetParent?(elem.offsetLeft+pageX(elem.offsetParent)):elem.offsetLeft;
}
window['zzc']['pageX'] = pageX;

function pageY(elem){
return elem.offsetParent?(elem.offsetTop+pageY(elem.offsetParent)):elem.offsetTop;
}
window['zzc']['pageY'] = pageY;
})();
function Drag(activeObj,dragObj,options){
     var aObj = zzc.$(activeObj);//激活元素
 var dObj = zzc.$(dragObj);//拖动元素
 var iDiffX = 0;
 var iDiffY = 0;
 var Options = options || {};
 var Limit = Options.Limit||false;
 var mxLeft = parseInt(Options.mxLeft)||0;//左边限制
 var mxRight = parseInt(Options.mxRight)||0;//右边限制
 var mxTop = parseInt(Options.mxTop)||0;//上边限制
 var mxBottom = parseInt(Options.mxBottom)||0;//下边限制
 var onMove = Options.onMove||function(){};//移动时执行 
 
(function start(){  
     zzc.addEvent(aObj,'mousedown',handleMouseDown);
 })();
 
function handleMouseMove(oEvent){ 
var oEvent = window.event || arguments[0];
var iLeft = oEvent.clientX - iDiffX, iTop = oEvent.clientY - iDiffY;
if(Limit){
var iRight = iLeft + dObj.offsetWidth - mxRight, iBottom = iTop + dObj.offsetHeight - mxBottom;
if(iRight > 0) iLeft -= iRight;
if(iBottom > 0) iTop -= iBottom;
if(mxLeft > iLeft) iLeft = mxLeft;
if(mxTop > iTop) iTop = mxTop;
 }
  
dObj.style.left = iLeft + 'px';
dObj.style.top = iTop + 'px';
onMove();
};
function handleMouseDown(oEvent){
         //清除选择(ie设置捕获后默认带这个)
     window.getSelection && window.getSelection().removeAllRanges();
 var oEvent = window.event || arguments[0];
 dObj.style.position = "absolute"; 
 iDiffX = oEvent.clientX - dObj.offsetLeft;
 iDiffY = oEvent.clientY - dObj.offsetTop;
 zzc.addEvent(document,'mousemove',handleMouseMove);
 zzc.addEvent(document,'mouseup',handleMouseUp);
 if(zzc.isIE()){
zzc.addEvent(dObj, "losecapture", handleMouseUp);
dObj.setCapture();
 }else{
zzc.addEvent(window, "blur", handleMouseUp);
 }
     };
function handleMouseUp(){
 zzc.removeEvent(document,'mousemove',handleMouseMove);
 zzc.removeEvent(document,'mouseup',handleMouseUp);
 if(zzc.isIE()){
zzc.removeEvent(dObj, "losecapture", handleMouseUp);
dObj.releaseCapture();
 }else{
zzc.removeEvent(window, "blur", handleMouseUp);
 }    
     };
}
//使图片滚动。
function picSlideByDrag(picBox,picList,dragObj,options){
     var Options = options || {};
 var mxLeft = parseInt(Options.mxLeft)||0;//左边限制
 var mxRight = parseInt(Options.mxRight)||0;//右边限制
 var mxTop = parseInt(Options.mxTop)||0;//上边限制
 var mxBottom = mxTop + dragObj.clientHeight;//下边限制
function init(){
var picListChild = zzc.$$(picList,'li');
var picListWidth = picListChild.length * picListChild[0].offsetWidth;
picList.style.width = picListWidth + 'px';
if(picListWidth <= picBox.clientWidth){
dragObj.style.display = "none";
}
    };
function picSlide(){
picList.style.left = -(((zzc.pageX(dragObj) - mxLeft)/(mxRight-mxLeft-dragObj.clientWidth))*(picList.clientWidth-picBox.clientWidth)) + "px";
};

init();
Drag(dragObj,dragObj,{Limit:true,mxTop:mxTop,mxRight:mxRight,mxBottom:mxBottom,mxLeft:mxLeft,onMove:picSlide});

};
window.onload = function(){
var picBox = zzc.$("picBox");
var picList = zzc.$("picList");
var scrollBar = zzc.$("scrollBar");
var dragObj = zzc.$("dragObj");
var initTop = zzc.pageY(scrollBar) + 1;
var initLeft = zzc.pageX(scrollBar) + 1;
var initRight = initLeft + scrollBar.clientWidth;
     picSlideByDrag(picBox,picList,dragObj,{mxTop:initTop,mxLeft:initLeft,mxRight:initRight});
}
</script> 
<br />
</body>
</html>