Go4Expert - How to filter out unwanted data

I have the following fields in table A:

Code:

Date            |  Descrip | Amt Dr  

---------------------------------- 

01/02/2006  |  740240  |(2,400.00)

14/02/2006  |  740241  |(3,000.00)

15/02/2006  |  41142   | 1,800.00         

20/02/2006  |  41142   | 2,700.00         

25/02/2006  |  740245  | 5,200.00

I have the following fields in table B:

Code:

Date            | Descrip |  Amt Dr  

---------------------------------- 

02/02/2006  |88258    |  1,400.00 

17/02/2006  |740244   | (1,500.00)

25/02/2006  |740245   |  5,200.00

There are no referencial key between TableA & TableB,
What i want is to extract the date,descrip & Amt data from
Table A where it's Descrip data is not the same as the data
in Table B's Descrip column.

My sql syntax is as follows:

Code: SQL

SELECT 
CASE WHEN TableA.Amt < 0 THEN TableA.[Date] ELSE 0 END, 
CASE WHEN TableA.Amt < 0 THEN TableA.Descrip ELSE 0 END, 
CASE WHEN TableA.Amt < 0 THEN TableA.Amt - (TableA.Amt * 2)ELSE 0 END AS [ADD Back]
FROM TableA,TableB
WHERE TableA.Descrip <> TableB.Descrip
GROUP BY TableA.Date,TableA.Amt,TableA.Descrip

The output of the above is as follows:

Code:

Date            | Descrip |  Amt Dr  

---------------------------------- 

01/02/2006  |  740240  |(2,400.00)

14/02/2006  |  740241  |(3,000.00)

15/02/2006  |    0         |     0

20/02/2006  |    0         |     0

25/02/2006  |  740245  |  5,200.00

Notice that, descrip with 740245 appearing in both tables
is what the sql should filter out, but failed to do so,
what i want is as below:

Code:

Date            | Descrip |  Amt Dr  

---------------------------------- 

01/02/2006  |  740240  |(2,400.00)

14/02/2006  |  740241  |(3,000.00)

Can i achieve this? Please help.