网页显示出错,这是那段代码，请高手帮忙！

Question

网页显示出错,这是那段代码，请高手帮忙<SCRIPT language=javascript>
    var ttime=0;
function huodong(tID) {
    var hdbig=$("focusL").getElementsByTagName("div");
for (var i=0;i<3;i++){
    var hdsmall=$("focusb"+i);
if (i==tID){
   hdbig[i].style.display="";
   hdsmall.style.filter="alpha(opacity=100)";
}
else{
   hdbig[i].style.display="none";
   hdsmall.style.filter="alpha(opacity=25)";
}
}
ttime++;
if (ttime>2){ttime=0}
}
function change(){
    huodong(ttime);
setTimeout('change()',3500);
}
change(ttime);
</SCRIPT>