Javascript function not working

i have a form with a select menu and if the user selects a certain option from the menu i want a new window to up up with the page i want. I already have the code for it, and i don’t see why it wouldn’t work. Any ideas?

javascript code:

<script type="text/javascript" language="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 =,myname,settings);
function pop_upVenue() {
	if(document.add_show.venue.options[document.add_show.venue.selectedIndex].value == 'add_venue') {
	newWindow('shows.php?mod=quick_vadd', 'Add Venue', '400', '350', 'scrollbars=no','resize=no');

html code:

<table border=\"0\" cellspacing=\"0\">
	<form id="add_show" name="add_show" method="post" action="shows.php">
		<tr bgcolor="#000000" style="font-size:9px;font-weight:bold;color:#ffffff;" align="center">
			<td colspan="2"><center>Add a Show</center></td>
		<tr bgcolor="#ffffff" style="font-size:9px;" align="center">
			<td width="80" align="left">Date:</td>
			<td><input style="width:100px;font-size:9px;font-family:verdana,arial;border:0px;background-color:#999999;color:#FFFFFF;" type="text" name="date" id="date" value="MM-DD-YYYY" />&nbsp;(MM-DD-YYYY)<input type="checkbox" name="tba" id="tba" value="true" />TBA</td>
		<tr bgcolor="#cccccc" style="font-size:9px;">
			<td width="80">Venue:</td>
			<td><select name="venue" class="selectmenu" onChange="pop_upVenue();"><option value="none"> - Choose Venue -</option><option value="1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Glasshouse - Pomona, CA</option><option value="add_venue">Venue Not Listed</option></select>