not all named parameters being set means that you have not assigned a value to all of your variables in your query.
say for example your query is
from Foo f where f.title=:title and f.author=:author and f.date=:date
your query must set the attributes for all 3 of the named attributes. The named attributes are the ones with the colons (:) in front of them.
Code:
Query q = new Query("from Foo f where f.title=:title and f.author=:author and f.date=:date");
q.setParameter("title", "Superman");
q.setParameter("author","bob");
q.setParameter("date","11.5.09");
List result = q.list();
the above is an example of how you would set your named parameters