select * from mytable where myfield=null;

Hi,
I'm using Postgresql 7.2.1, with JBoss2.4.4. and jdk1.4

Here is my table :
id   |  date                   |   value
-----+-------------------------+---------
   1 | 2002-05-10 10:00:00:+02 |       5
   2 |  (null)                 |      10
...

With the jdbc driver, this query doesn't any result :
Stmt = con.prepareStatement(select * from mytable where date=?)
Stmt.setNull(1,java.sql.Types.TIMESTAMP);
Stmt.executeQuery();

I think the jdbc driver transform the query on "select * from mytable 
where date=null" and not "select * from mytable where date is null".

Il seems that select * from mytable where date=null was supported by 
postgres before 7.0 version, but not with the 7.2.1

How can i do ?
thanks
Bruno.