Navigation in javaHelp

Hi,

I create with saxon and the xsl-styles 1.65.1 javaHelp out of
my docBook files. I don't get the navigation-buttons in
the single html sides in the viewer, like in normal chunked
html sides. I set the following parameters:
<xsl:param name="navig.graphics" select="1"/>
<xsl:param name="navig.graphics.extension" select="'.png'"/>
<xsl:param name="navig.graphics.path">images/</xsl:param>

What did I make wrong?
Thank you for any help.

Regards
Melanie R飉ch