max question

I have the following in a table:  oid   |   citkey   |  contby  |  contdate  | abcontinue |   ccdate  
---------+------------+----------+------------+------------+------------5774835 | 04-0594703 |          |            |
         |5775325 | 04-0594703 | Attorney | 04/06/2005 | 6          | 03/07/20055776060 | 04-0594703 | Attorney |
05/04/2005| 6          | 04/05/20055776067 | 04-0594703 | Attorney | 05/04/2005 | 6          | 04/05/2005
 

I am trying to pull rows that have the max. contdate. Why does the 
following give more than 2 rows?ql "select oid,* from ccontinue where citkey ='04-0594703' group by 
oid,citkey,contby,contdate,abcontinue,ccdate having max(contdate) = 
contdate"  oid   |   citkey   |  contby  |  contdate  | abcontinue |   ccdate  
---------+------------+----------+------------+------------+------------5776067 | 04-0594703 | Attorney | 05/04/2005 |
6         | 04/05/20055775325 | 04-0594703 | Attorney | 04/06/2005 | 6          | 03/07/20055776060 | 04-0594703 |
Attorney| 05/04/2005 | 6          | 04/05/2005
 
(3 rows)

thanks