[Docbook XSL pack][FOP]Error on exsl(t).node-set

[Hélia Pouyllau <helia.pouyllau@softeam.fr>]

Hi,

I'm trying to use the docbook xsl pack with FOP in a java application 
and I encountered the following error :
[ERROR] Unsupported element encountered: html (Namespace: default). 
Source context: unavailable
[ERROR] Expected XSL-FO (root, page-sequence, etc.), SVG (svg, rect, 
etc.) or elements from another supported language.
java.lang.RuntimeException: java.lang.NullPointerException
    at 
org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java:3407)
    at 
org.apache.xalan.transformer.TransformerHandlerImpl.endDocument(TransformerHandlerImpl.java:433)
    at org.apache.xerces.parsers.AbstractSAXParser.endDocument(Unknown 
Source)
    at org.apache.xerces.impl.dtd.XMLDTDValidator.endDocument(Unknown 
Source)
    at org.apache.xerces.impl.XMLDocumentScannerImpl.endEntity(Unknown 
Source)
    at org.apache.xerces.impl.XMLEntityManager.endEntity(Unknown Source)
    at 
org.apache.xerces.impl.XMLEntityManager$EntityScanner.load(Unknown Source)
    at 
org.apache.xerces.impl.XMLEntityManager$EntityScanner.skipSpaces(Unknown 
Source)
    at 
org.apache.xerces.impl.XMLDocumentScannerImpl$TrailingMiscDispatcher.dispatch(Unknown 
Source)
    at 
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown 
Source)
    at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
    at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
    at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
    at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
    at org.apache.xalan.transformer.TrAXFilter.parse(TrAXFilter.java:134)
    at org.apache.fop.apps.Driver.render(Driver.java:498)
    at GeneratePDF.run(GeneratePDF.java:51)
    at AppTest.main(AppTest.java:47)

Then I tried to launch with a console and i get this error :
[ERROR] java.lang.NoSuchMethodException: For extension function, could 
not find
method 
org.apache.xml.dtm.ref.DTMNodeIterator.node-set([ExpressionContext,] ).

I use the following versions :
FOP : 0.20.5
Docbook-xsl : 1.65.1

The problem seems to come from the xalan processor of FOP and the fact 
Docbook-xsl used EXSLT. But as I'm a little bit lost, I don't really know.
I found some advices on the web but nothing worked, therefore could 
someone explain me the problem I have and how to solve it.

Thanks in advance
HP