Xincludes and Peer Section Ordering

[Raymond <support@bigriverinfotech.com>]

docbook-dtd-4.5CR1, docbook-xsl-1.69.1, jdk-1.5.0_4, kubuntu-5.04, oXygen-6.1, 
saxon-6.5.4

Consider the following code fragement:

<sect1 id="foo" xmlns:xi="&w3XInclude;" xml:base="">
      <title>Foo</title>
  <sect2>
      <title>Bar1</title>
      <para>foo</para>      
   </sect2>
   <xi:include href="file:///_foo_/Bar2.xml">
      <xi:fallback>
         <simpara>
            <emphasis role="strong">FIXME:</emphasis> MISSING
               /_foo_/<emphasis>Bar2.xml</emphasis> XINCLUDE
         CONTENT</simpara>
      </xi:fallback>
   </xi:include>
</sect1>

the Xinclude'd fragement:

<sect2 id="bar1" xmlns:xi="&w3XInclude;" xml:base="">
...
...
</sect2>

Why do the following validation error messages:

Unexpected element "xi:include".

and

The content of element type "sect1" must match "(sect1info?,
(title,subtitle?,titleabbrev?),(toc|lot|index|glossary|bibliography)* ...

occur ONLY when sect2  precedes the xinclude and not subsequent ???

Raymond