SQL Problem

Has anyone ever seen this error before? Any advice as to an alternate method without having to create temporary tables would be appreciated. Thanks.

INSERT INTO ACTPROD_ALLOC_DEN
SELECT C.SOURCE_ITEM,

   SUM((A.Q1*B.Y1*D.Y1)*((1+E.Y1Q1)/2),
   SUM((A.Q2*B.Y1*D.Y1)*((1+E.Y1Q2)/2),
   SUM((A.Q3*B.Y1*D.Y1)*((1+E.Y1Q3)/2),
   SUM((A.Q4*B.Y1*D.Y1)*((1+E.Y1Q4)/2)
FROM THRUPUT A, ACTIVITY_DRIVERS B, ACT_PROD_METH C,
     MACHINE_HOURS D, DETAILYIELDS E,
WHERE A.MENUPRODUCT=B.MENUPRODUCT AND
      B.MENUPRODUCT=C.MENUPRODUCT AND
      C.MENUPRODUCT=D.MENUPRODUCT AND
      D.MENUPRODUCT=E.MENUPRODUCT AND
      A.SECTOR=D.SECTOR AND
      D.SECTOR=E.SECTOR AND
      A.SECTOR=11 AND
      C.ALLOC_METH=B.DRIVER_TYPE AND
      B.DRIVER_TYPE='HR MHRS' AND