NoSuchMethodError in named template

[Andreas Hartmann]

Hi Xalan users,
I'm running the following setup:
- Lenya CVS
- Cocoon 2.1 Release
- Tomcat 5.0.9
- xalan-j_20030826 as endorsed libraries
and get the following error:
java.lang.NoSuchMethodError: 
page2xhtml.getdocument(Lorg/apache/xalan/xsltc/DOM;Lorg/apache/xml/dtm/DTMAxisIterator;Lorg/apache/xml/serializer/SerializationHandler;I)V
	at page2xhtml.language$dash$link()
	at page2xhtml.topnavbar()
	at page2xhtml.applyTemplates()
	at page2xhtml.applyTemplates()
	at page2xhtml.transform()
	at 
org.apache.xalan.xsltc.runtime.AbstractTranslet.transform(AbstractTranslet.java:545)
	at 
org.apache.xalan.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:671)

The template named "getdocument" does exist.
How can I trace this error?
It does not happen with Tomcat 4.1.24 and the same Xalan version.
Thanks in advance!
Andreas