> I guess I have meserably failed to explain the problem clearly.
> 
> here is the actual snippet that illustrates the problem.

It would certainly have been useful to supply this information originally,
but it only confirms the original diagnosis: the extension function you are
calling is designed to do a quite different job from the job that you want
done. (And I've no idea what job you _do_ want done...)

Michael Kay
http://www.saxonica.com/