Hi Teacher.

I'm trying to get with Xpath the Product nodes in the following XML:
<?xml version="1.0" encoding="utf-8"?>
<PLMXML xmlns="http://www.plmxml.org/Schemas/PLMXMLSchema"
 schemaVersion="5.1" date="2005-05-03" time="16:41:33" author="TcEng -
infodba@bridge(389284449)">
<Header id="id1" traverseRootRefs="#id2 #id11"
transferContext="exp_folder"></Header>
<Product id="id10" name="Ace" accessRefs="#id3" subType="Drawing"
productId="000002">
<ApplicationRef version="QRJJ3Vh1xNEIWA" application="TcEng"
label="QRJJ3Vh1xNEIWA"></ApplicationRef>
<UserData id="id33">
<UserValue type="reference" value="" title="owning_user"
dataRef="#id11"></UserValue>
<UserValue value="0-01-00T00:00:00" title="date_released"></UserValue>
<UserValue value="2005-05-03T14:00:32"
title="last_mod_date"></UserValue>
<UserValue type="reference" value="" title="last_mod_user"
dataRef="#id11"></UserValue>
<UserValue type="reference" value="" title="owning_group"
dataRef="#id27"></UserValue>
<UserValue value="2005-05-03T10:46:39"
title="creation_date"></UserValue></UserData></Product> (Continue...)

I've used the /PLMXML/Product query but I can't get anything.

I've also tried  this simple xml:
<?xml version='1.0'?>
<Books>
<Book>
  <Title>Beginning XML</Title>
  <Publisher>Wrox</Publisher>
</Book>
<Book>
  <Title>XML Step by Step</Title>
  <Publisher>MSPress</Publisher>
</Book>
<Book>
  <Title>Professional XML</Title>
  <Publisher>Wrox</Publisher>
</Book>
<Book>
  <Title>Developing XML solutions</Title>
  <Publisher>MSPress</Publisher>
</Book>
</Books>

And on this Xml the rule /Books/Book works fine.

Why does not the first rule work?
Am I missing something? 

Thanks in advance.
Marco.