XML/XSL and libxslt ISSUES

Hi,
 
My Environnment :
 
Wamp Serveur runing on winXP sp2 -> http://www.wampserver.com/ seems to
use libxslt as XSLT Processor.
 
 
I am trying to generate dynamically a news page from news.xml & news.xsl
files using php5, the problem I have is that my news.xml include an
external xml file using <!ENTITY>(external file is named
menu_gauche.xml). 
 
So when i generate the page, all the content present in news.xml is
displayed correctly according to news.xsl, but none of the content from
menu_gauche.xml is displayed...
 
The strange thing is that when I generate my news page from the exact
same files (news.xml and news.xsl) using the XSLT Processor of my
developpment tool (Saxon6.5.3) it works and the page is as I expect it
to be.
 
So I guess there is a problem with libxslt ?
 
Sorry for this long post, but I've tried many, many, workaround without
success :-(
 
If Anyone Can help :-)
 
Thanks in advance for your answers.
 
Fp
 
Samples of my Code :
 
here is the php5 code I use for generation :
 
<?
$moteurXslt = new xsltProcessor();

$style = new domDocument();
$style->load('news.xsl');

$moteurXslt->importStylesheet($style);

$source = new domDocument();
$source->load('news.xml');

echo $moteurXslt->transformToXml($source);
?> 
 
here is the declaration of my external xml file:
 
<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet href="news.xsl" type="text/xsl"?>
<!DOCTYPE PAGE [<!ENTITY menu_gauche SYSTEM 'menu_gauche.xml'><!ENTITY
copy "&#169;" ><!ENTITY nbsp "&#x00A0;" > ]> <PAGE>
    <!-- Include the left menu-->&menu_gauche; <NEWS>
        <BLOCK>
            <TITRE>NEWS</TITRE>....
....