Adding Sub Menu's by hand, how?

I just need to add a sub menu by hand to an existing menu, but when I have tried it, it does not validate.

<ul class="level-0" id="cssmw">
<li><span><a href="index.html">Home</a></span></li>
<li><span><a href="about.html">About Us</a></span></li>
<li><span><a href="contact.html">Contact Us</a></span></li>
<li><span><a href="#">Useful Links</a></span></li>
</ul>

Let’s just say I would like to add 2 sub menus under 'Useful Links' and we'll name them, 'Nation Government' and 'Regional Government' how is it achieved?

As I said, I did try something which gave me something like a 'minus one level', <ul class="level-1" id="cssmw"> but it didn’t validate even using transitional validation.

Regards
Alan

Hi. I just discovered, just to chip in, that if you hand edit the menu, when you come to edit it again with the CSS Menu Writer wizard it will cause problems.

I had an eight button menu that I'd created by hand in the menu.asp file but when I opened the wizard it only displayed 3 buttons and I had to rebuild it all over again.

For your information though, here's a two button menu with a sub-menu beneath the second item:

<ul class="level-0" id="cssmw">
<li><a href="<%=assumedRoot%>index.asp">Home</a></li>
<li class="parent"><a href="<%=assumedRoot%>instruments.asp">Instruments</a>
<ul class="level-1">
<li><a href="<%=assumedRoot%>violin-instruments.asp">Violins</a></li>
<li><a href="<%=assumedRoot%>viola-instruments.asp">Violas</a></li>
<li><a href="<%=assumedRoot%>cello-instruments.asp">Cellos</a></li>
</ul>
</li>
</ul>

Hope that's useful anyway.
Regards
Nathon.

Thanks Nathan, that did give me a 'heads up' and with your help I've solved it now.