ZK HibernateUtil not working at SessionInit

Session currentSession() {
        return HibernateUtil.currentSession();
    }

public class SessionInitiator implements SessionInit {

    @Override
    public void init(Session sn, Object o) throws Exception {
           ...
           User user = new AuthDAO().findUserByUsername("a_user_name");
           sn.setAttribute("user", user);//set user to session
           ...
    }
}

WARNING: StandardWrapperValve: PWC1406: Servlet.service() for servlet auEngine threw exception
org.hibernate.HibernateException: get is not valid without active transaction
	at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:297)
	at $Proxy132.get(Unknown Source)
	at com.digstree.auth.data.AuthDAO.findUserByUsername(AuthDAO.java:42)
	at com.digstree.ui.init.SessionInitiator.init(SessionInitiator.java:23)
	at org.zkoss.zk.ui.util.Configuration.invokeSessionInits(Configuration.java:772)
	at org.zkoss.zk.ui.http.SimpleSession.<init>(SimpleSession.java:154)
	at org.zkoss.zk.ui.http.SimpleSession.<init>(SimpleSession.java:112)
	at org.zkoss.zk.ui.http.SimpleUiFactory.newSession(SimpleUiFactory.java:35)
	at org.zkoss.zk.ui.sys.SessionsCtrl.newSession(SessionsCtrl.java:150)
	at org.zkoss.zk.ui.http.WebManager.getSession(WebManager.java:404)
	at org.zkoss.zk.ui.http.WebManager.getSession(WebManager.java:398)