DocBook assembly generation: missing top-level titles

[graeme@heliocentrik.net]

Hi there,
I'm using version 1.78.1 of the DocBook stylesheets to generate articles
from DocBook assembly. Which is nice! But here's my problem: top-level
element titles are missing from the output.

Given this structure, the output is lacking its top-level element title
(in this case, the article title):

<?xml version="1.0"?>
<assembly xmlns:xlink="http://www.w3.org/1999/xlink";
xmlns="http://docbook.org/ns/docbook";>
	<resources xml:base="topics/reference">
		...
    </resources>
	<structure xml:id="guide">
		<output renderas="article"/>
		<info>
			<title>My Article Title</title>
		</info>
		<module renderas="section">
			<info>
				<title>My Section</title>
			</info>
			<module resourceref="guide-articles"/>
			<module resourceref="guide--lists"/>
		</module>
		<module resourceref="guide-thing1"/>
		<module resourceref="guide-thing2"/>
		<module resourceref="guide-thing3"/>
	</structure>
</assembly>

Here's the snipped output of assemble.xsl:

<?xml version="1.0"?>
<article xmlns="http://docbook.org/ns/docbook"; version="5.0"
xml:id="guide">
	<section>
		<section version="5.0">
			<info>
				<title
				xmlns:xlink="http://www.w3.org/1999/xlink";
				xmlns:xi="http://www.w3.org/2001/XInclude";
				xmlns:svg="http://www.w3.org/2000/svg";
				xmlns:mml="http://www.w3.org/1998/Math/MathML";
				xmlns:html="http://www.w3.org/1999/xhtml";
				xmlns:db="http://docbook.org/ns/docbook";>Thing
				1</title>
			</info>
			<para>The text of thing1</para>


I don't quite understand how it could miss out this detail.

I'm using xsltproc to run the stylesheet transformation.

Any help would be appreciated.

Thanks,

Graeme