## Problem with date and INTERVAL

Hi all.

I have problem with this query.
In my table mysql `tbl_d` the value of the field `myDate` is 2011-05-23.

Code:
```SELECT d.LOCK, d.myDate, x.dt
FROM tbl_d AS d

CROSS JOIN (
SELECT
CASE

#case 1
WHEN SUM(CASE WHEN MONTH(myDate) = MONTH(CURRENT_DATE)
AND YEAR(myDate) = YEAR(CURRENT_DATE) THEN 1 ELSE 0 END)
> 0 THEN CURRENT_DATE

#case 2
WHEN SUM(CASE WHEN MONTH(myDate) = MONTH(CURRENT_DATE -1)
AND YEAR(myDate) = YEAR(CURRENT_DATE) THEN 1 ELSE 0 END)
> 0 THEN CURRENT_DATE - INTERVAL 1 MONTH

#case 3
WHEN SUM(CASE WHEN MONTH(myDate) = MONTH(CURRENT_DATE -2)
AND YEAR(myDate) = YEAR(CURRENT_DATE) THEN 1 ELSE 0 END)
> 0 THEN CURRENT_DATE - INTERVAL 2 MONTH

#last case
ELSE CURRENT_DATE - INTERVAL 3 MONTH
END AS dt
FROM tbl_d) AS x

WHERE 1

AND MONTH(d.myDate) = MONTH(x.dt)
AND YEAR(d.myDate) = YEAR(x.dt)

GROUP BY d.LOCK
ORDER BY d.LOCK ASC```
The sql debug:
#case 1 ---> 5 = 7 false;
#case 2 ---> 5 = 6 false;
#case 3 ---> 5 = 5 true;

Affected rows: 0
Time: 0.110ms

Why? Always in the #last case?
Thanks in advance, any help is very appreciated.