Date format in query

Hi!
My query doesn't answer like would be.
This is the code:

s=string(today(),'dd/mm/yyyy')+' 08:00'

SELECT COUNT("ID_KEY")
    FROM "DIARIOCLI"
    WHERE
    to_char("DATE_REG",'dd/mm/yyyy hh24:mi') >= :s ; //'01/07/2003 08:00'

In my table there are only 5 rows where the date is 30 June 2003 and my query returns 5 rows.
Where I wrong??
Please, can someone help me?
Bye
Paola Received on Tue Jul 01 2003 - 04:04:48 CDT