DOCBOOK: Xref ID problem

["E.L. Willighagen" <egonw@sci.kun.nl>]

Hi all,

why does this not work?

<?xml version="1.0"?>
<book>
  <bookinfo>
    <title>Some Documentation</title>
  </bookinfo>

  <chapter>
    <title>Command Line Options</title>
    <section>
      <para>
        This makes it possible to start jmol with a Rasmol script.
        The syntax of these scripts is explained in <link linkend="ch02"/>.
      </para>
    </section>
  </chapter>

  <chapter id="ch02">
    <title>Rasmol Scripts</title>
    <section>
      <title>General Commands</title>
      <section>
        <title>load</title>
        <para>
	  <cmdsynopsis>
	    <command>load</command>
	    <arg>format</arg>
            <arg choice="req"><replaceable>filename</replaceable></arg>
	  </cmdsynopsis>
	</para>
        <para>
          Currently accepted formats are PDB, CML and XYZ.
        </para>
      </section>
    </section>
  </chapter>
</book>

when compiling with XT and norman's xsl stylesheets, i get this error:

file:/home/egonw/CVS/Jmol/doc/source/text.xml:12: Error: no ID for constraint linkend: ch02.

What is wrong with <chapter id="ch02">??

Egon