Ranking results

I am trying to figure out how to rank sales figures. The report would
return Q4 sales for 2009, 2009, 2007 with rankings varying for each year
depending on sales. I was trying to use Rank() but " An OLAP function
is not supported for this query.".

SELECT
AMFLIB . CUSMAS . CUSNO AS "Customer Number" , AMFLIB . CUSMAS .
CUSNM AS "Customer Name" ,
SUM ( CASE WHEN AMFLIB . MBF9REP . FEGHNB BETWEEN 1091001 AND
1091231 THEN AMFLIB . MBDDREP . DDDUVA ELSE 0 END ) AS "QE 12/31/09" ,
0 AS "RANK 1",
--RANK() OVER (ORDER BY SUM ( CASE WHEN AMFLIB . MBF9REP .
FEGHNB BETWEEN 1091001 AND 1091231 THEN AMFLIB . MBDDREP . DDDUVA ELSE 0
END ) ) AS "RANK 1",
SUM ( CASE WHEN AMFLIB . MBF9REP . FEGHNB BETWEEN 1081001 AND
1081231 THEN AMFLIB . MBDDREP . DDDUVA ELSE 0 END ) AS "QE 12/31/08" ,
0 AS "RANK 2",
SUM ( CASE WHEN AMFLIB . MBF9REP . FEGHNB BETWEEN 1071001 AND
1071231 THEN AMFLIB . MBDDREP . DDDUVA ELSE 0 END ) AS "QE 12/31/07" ,
0 AS "RANK 3",
SUM ( CASE WHEN AMFLIB . MBF9REP . FEGHNB BETWEEN 1100101 AND
1100331 THEN AMFLIB . MBDDREP . DDDUVA ELSE 0 END ) AS "QE 03/31/10" ,
0 AS "RANK 4",
SUM ( CASE WHEN AMFLIB . MBF9REP . FEGHNB BETWEEN 1090101 AND
1090331 THEN AMFLIB . MBDDREP . DDDUVA ELSE 0 END ) AS "QE 03/31/09" ,
0 AS "RANK 5",
SUM ( CASE WHEN AMFLIB . MBF9REP . FEGHNB BETWEEN 1080101 AND
1080331 THEN AMFLIB . MBDDREP . DDDUVA ELSE 0 END ) AS "QE 03/31/08",
0 AS "RANK 6"
FROM
AMFLIB . CUSMAS
-- Shipment Header
JOIN AMFLIB . MBDHREP
ON AMFLIB . CUSMAS . CUSNO = AMFLIB . MBDHREP .
DHCANB
-- Shipment Details
JOIN AMFLIB . MBDDREP
-- ON Shipment #
ON AMFLIB . MBDHREP . DHZ969 = AMFLIB . MBDDREP
. DDZ969
-- Invoice Header
JOIN AMFLIB . MBF9REP
-- ON Invoice #
ON AMFLIB . MBF9REP . FEGGNB = AMFLIB . MBDHREP
. DHGGNB
WHERE

AMFLIB . MBDDREP . DDAXNB = 1 OR AMFLIB . MBDDREP . DDAAF4 = 1
GROUP BY
AMFLIB . CUSMAS . CUSNO ,
AMFLIB . CUSMAS . CUSNM
ORDER BY
"QE 12/31/09" DESC
FETCH FIRST 50 ROWS ONLY;