Possible bug in XHTML 1.1 validator?

Dear list members,

I'm teaching Web Technologies to graduate students, One of my students  
tried to validate the  following XHTML 1.1 document, without success  
but even without errors explained:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC"-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Titolo del documento</title>
</head>
<body>
<h1>Ciao a tutti!</h1>
<p>vediamo</p>
<h2>bla bla bla</h2>
<p>Questao e un paragrafo.Se volessi introdurre un
a-capo  dovrei usare l elemento br.</p>
<p>parole   separate   da   spazi.</p>
<pre>parole   separate   da   spazi.</pre>
<p>Gli <em>elementi di frase </em>stanno solo dentro
gli elementi di tipo block, come <strong>p </strong>o
<strong>pre </strong>.</p>
<p>Cosi funziona <acronym title="eXtensible Hyper Text
Markup Language">XHTML</acronym>...</p>
<p>Come dice <cite>H.Simpson</cite>, <q
cite="http://www.simpson.com/">provare e il primo
passo verso il fallimento.</q></p>
</body>
</html>

The validator answer is:

File:  zahtila.html
Content-Type: text/html
Encoding: utf-8
Doctype: XHTML 1.1
This page is not Valid XHTML 1.1!

Below are the results of attempting to parse this document with an SGML  
parser.

And then, it shows only the source.

I looked more and more at the file, but I'm not able to find any error.  
May be is a bug in the validator?

Thanks,

VIncenzo Della Mea

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-----------------------------  Vincenzo Della Mea, PhD  
------------------------------
Dept. of Mathematics and Computer Science - University of Udine, Italy
-----------------------  http://www.dimi.uniud.it/~dellamea/  
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Received on Friday, 28 February 2003 04:34:02 UTC