Unable to get object from datastore using objectify

Question

I am working on a simple expenses manager that will be deployed on google appengine. I am using objectify as Appengine ORM. now the problem is that I am unable to get a simple Object from datastore. The Session here is always null !! But when I check it out in localhost datastore I can see that it is there !

@Override
public String findEmailBySessionId(String sid) {
    Session session = datastore.load().type(Session.class).id(sid).now();
    if (session != null && (session.getDate().after(new Date()) || session.isToBeRemembered())) {
        return session.getEmail();
    }   // this is always null !
    return null;  
} 

---

@Entity
public class Session {


    private String email;

    @Id
    private String sessionId;

    private Date date;

    private boolean toBeRemembered;

    @Parent
    private Key<User> parent;
......... 
} 

---

@Entity
public class User {

    @Id
    private String email;

    private String name;
    private String password;
    private Date dateOfBirth;
    private String hashSalt;

    public User() {
    }

Answer 1

Ok, I've got the answer and it is very silly. It is actually very stupid.

In google documentation there is a restriction on query that says:

*Filtering on unindexed properties returns no results !!!! * link For objectify to index a property that property should be annotated with @Index annotation. In the code above I forgot to put @Index annotation on date ! And this was the problem. After I put the annotation back everything returned to normal.