Are lists not processed correctly?

I have the following list:
<ul>
	<li>
		<b>Heading 1</b><br>
		Description
	</li>
	<ul>
		<li><b>SubHeading 1</b></li>
		<ul>
			<li>
				<a href="link">Link 1</a><br>
				Link Info<br>
				Link Description<br>
			</li>
			<li>
				<a href="link">Link 2</a><br>
				Link Info<br>
				Link Description<br>
			</li>
		</ul>
		<li><b>SubHeading 2</b></li>
		<ul>
			<li>Description</li>
		</ul>
	</ul>
</ul>

With the </li> this will not validate correctly.  If I comment out the </li>
it validates fine.  Is there a problem with the validator?

B. Collier Jones
brjones3@vt.edu