Bookmark Code - NETSCAPE

Hello:
I posted this question earlier and got help with the code necessary to
display Bookmark variations for different browsers:
a hyperlink for IE, and "Ctrl + D" for Netscape and FireFox

For some reason the code works fine in IE and FireFox but absolutely refuses
to work in Netscape:

<script type="text/javascript">
if ((navigator.appName == "Microsoft Internet Explorer") &&
(parseInt(navigator.appVersion) >= 4)) {
var url="http://www.mywebsite.com/";
var title="Description";
document.write('<A HREF="javascript:window.external.AddFavorite(url,title)');
document.write('"<font color=#FFFFF4 face=tahoma size=8pt><b>Click to
Bookmark</b></font></a>');}
else {var alt = "<font color=#FFFFF4 face=tahoma size=2pt><b>To
bookmark<b/></font>";
if(navigator.appName == "Netscape") alt += "<font color=#FFFFF4 face=tahoma
size=2pt><b> - Ctrl+D<b/></font>";
document.write(alt);}
</SCRIPT>

Does anyone know why Netscape does not like this code?

Thank you!