Indexterm in sectinfo, no entries for index key

["Thomas, Ludger" <Ludger.Thomas@iese.fraunhofer.de>]

Hi all,
I´m using the 1.68.0 Version of the Docbook XSL Stylesheets and XEP 4.2 build 20050220 to build my PDFs.

When I try to transform valid Docbook-Code like

sect1
	sect1info
		keywordset
			keyword
		indexterm
			primary
			secondary
	title
	
to FO and then to PDF, XEP returns a "no entries for index key" error. This code works fine

sect1
	sect1info
		keywordset
			keyword
	title
	indexterm
		primary
		secondary

Is this a bug or did I get something wrong? Any hints?

Thanks and best wishes.
Ludger Thomas