As a very quick response, I'd say that most grammar problems come back to some mis-matched mapping from the xml/annotations to the database. Maybe name problem? Incompatible mapping?
Just a hint, but be more descriptive in the old subject like. Most questions in here are about hibernate3. Be more descriptive, and someone that knows the answer might pipe up, as opposed to just passing it by because they are not experts on hibernate3 specifically. Help us help you!