Index with htmlhelp.xsl

Hi everybody,

I like to parse a docbook with xsltproc and the htmlhelp-stylesheet. In
e.g. xChm there is a “table of contents”-tab and a searchtab and also an
index-tab. According information from the last decade in the internet
about xsl, an index should be created automatically. But it isn´t. The
index-tab in xChm is empty for my converted docbooks. 
It worked to add a manual index with this parameter.
<xsl:param name="htmlhelp.use.hhk" select="1"></xsl:param>
Then I had to add indexterm-tags manually to each article. 
How can I automatically create an index that can be used by the
chm-compiler? 


Thanks a lot,

Timo