ORDER BY interferes with DISTINCT keyword

[lis0x90]

I use dynamic EJB-QL clauses in JBoss 4.0.3 and have folowing queries:

select distinct object(o) from orders as o, in(o.actions) as a order by o.state desc
select distinct object(o) from orders as o, in(o.actions) as a order by a.insertTime desc, o.state desc

In sectond query a get rowset that have duplicate results. When I see to logs:

2006-05-03 20:17:20,578 DEBUG [org.jboss.ejb.plugins.cmp.jdbc.JDBCDynamicQLQuery.Order#ejbSelectFilteredOrders] Executing SQL:
SELECT DISTINCT t0_o.OrderId, t0_o.State FROM Orders t0_o, Actions t3_a ORDER BY t0_o.State DESC
...
2006-05-03 20:17:20,578 DEBUG [org.jboss.ejb.plugins.cmp.jdbc.JDBCDynamicQLQuery.Order#ejbSelectFilteredOrders] Executing SQL:
SELECT DISTINCT t0_o.OrderId, t3_a.InsertTime, t0_o.State FROM Orders t0_o, Actions t3_a ORDER BY t3_a.InsertTime DESC, t0_o.State DESC

Field t3_a.InsertTime became in select clause and causes duplicate rows in result set!

What should I do to avoid its strange behaviour?
Thanks for any help.

[lis0x90]

So anybody knows any answer on my question?

Why fields added to ORDER BY clause appears in SELECT section and mar up result set?