HierarchicalStreamDriver not found

Executing a jar file throws exception.
No implementation of HierarchicalStreamDriver seems to be loadable.

It works fine when executed within Eclipse 3.1
but when exported to a jar it throws exception, when executed :

G:\temp>java -jar xx.jar
Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: com/thoughtworks/xstream/io/HierarchicalStreamDriver
...

I tried both with a default domdriver as
XStream xstream = new XStream(new DomDriver());

and included xpp3

but no difference; fine in Eclipse but not at all in standalone jar.

Perhaps there is some other jar that is missing ?