คำสั่ง Window.Open() ไม่ทำงานบน IE8 รบกวนผู้รู้ช่วยทีครับ

function popup(){
var l =(screen.width)?(screen.width-500)/2:100;  
var t =(screen.height)?(screen.height-400)/2:100;   
javascript:window.open('email_add_form.html','new','width=500,top='+t+',left='+l+',height=400');
}

<script type="text/JavaScript">
var win = null;
function newWindow(mypage,myname,w,h,features) {
  var winl = (screen.width-w)/2;
  var wint = (screen.height-h)/2;
  if (winl < 0) winl = 0;
  if (wint < 0) wint = 0;
  var settings = 'height=' + h + ',';
  settings += 'width=' + w + ',';
  settings += 'top=' + wint + ',';
  settings += 'left=' + winl + ',';
  settings += features;
  win = window.open(mypage,myname,settings);

}
</script>