here is my function:

<script Language="JavaScript">
function openWin(fileName, w, h) {

windowName = 'HalstonsJewelry-Gifts.com';
windowProps = 'height=' + h + ',width=' + w + ',toolbar=no,status=yes,scrollbars=yes,menubar=no,resizeable=yes';
win = window.open(fileName, windowName, windowProps);

if (parseInt(navigator.appVersion) >= 4) {
win.window.focus();
}
}
</script>

here is what i'm calling it with:
<a href='javascript:' onClick='openWin("pop.php",250,300);' class='link_red'>

the error i consistently get is the following:

Line 45 error. (that's the line with the win = window.open(fileName,windowName, windowProps);

Invalid Argument?

I can't figure it out.