DOCBOOK-APPS: Error with Docbook XSL

[adsingh]

Hi

While converting an XML file  (docbook DTD)  into HTMl, using the stylesheet
/docbook/html/docbook.xsl
I get the error in the file index.xsl  line 273 ,    Error  is    no such
fuction: key.


I'm using James Clark's   XT to transfrom XML to HTML.
Cld someone pl help me wiht this ?

Regards aman