> I have tried debugging this code with no luck!

Then please follow the advice I gave you before.
> >
> > Create a simplified example that demonstrates the problem but is 
> > complete, so anyone can run it. You might find the bug while you're 
> > doing that, of course.
> >
> > Regards,
> >
> > Michael Kay
> > http://www.saxonica.com/
> > http://twitter.com/michaelhkay