I am trying to display a image in a window pop up using the following javascript

```
function newPopup(url) {
    popupWindow = window.open(
        url,'popUpWindow','height=700,width=800,left=10,top=10,resizable=yes,scrollbars=no,toolbar=no,menubar=no,location=no,directories=no,status=yes')
}

```

In the Html code I am using php directory Iterator to find jpeg image and pass it to the javascript. But the pop up window does not open. 

```
echo '<td width="150"><a href="JavaScript:newPopup('.$file_name.');">ScreenShot</a></td>';

```

What am I doing wrong here