Problem with the following SQL statement

Hi,

When I goto Activate the ABAP program the following error pops up for the SQL statement below;

DATA: total_shipping TYPE p DECIMALS 2.

SELECT SUM( KWERT )

INTO total_shipping

FROM KONV

WHERE KNUMV = '0000001104' and KSCHL = 'ZKF0'.

Error - "Aggregate functions and the addition DISTINCT are not supported in field lists for pooled and cluster tables."

What could be the solution be?

Thanks,

Kishan