[SQL] max question

[A. R. Van Hook]

I have the following in a table:
  oid   |   citkey   |  contby  |  contdate  | abcontinue |   ccdate  
---------+------------+----------+------------+------------+------------
5774835 | 04-0594703 |          |            |            |
5775325 | 04-0594703 | Attorney | 04/06/2005 | 6          | 03/07/2005
5776060 | 04-0594703 | Attorney | 05/04/2005 | 6          | 04/05/2005
5776067 | 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          | 04/05/2005
5775325 | 04-0594703 | Attorney | 04/06/2005 | 6          | 03/07/2005
5776060 | 04-0594703 | Attorney | 05/04/2005 | 6          | 04/05/2005
(3 rows)

thanks
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