Hibernate detached criteria issue

Question

I am trying to execute the following query using hibernate criteria. But, it is not giving me correct results.

Query:

SELECT * 
FROM   TableA a 
WHERE  NOT EXISTS (SELECT * 
               FROM   TableB b 
               WHERE  b.col1 = a.col1 
                      AND b.flag = 'Y');

Hibernate:

Criteria criteria = session.createCriteria(TableA.class, "a");
DetachedCriteria dc = DetachedCriteria.forClass(TableB.class, "b");
dc.add(Property.forName("b.col1").eqProperty("a.col1"));

dc.add(Restrictions.eq("b.flag","Y"));
dc.setProjection(Property.forName("b.col1"));

criteria.add(Subqueries.notExists(dc));

---

The query it is generating is-

select * from TableA a where not exists (select b.col1 from TableB b where **b.col1=b.col1** and b.flag='Y');

Here, I am not sure why it is comparing b.col1 with b.col1.

Can someone please help in fixing this issue. Thanks in advance.

-- Teja.