Let's Try again:
Select A.*, Sum(B.x) as Calc_Amt ;
From A, B ;
Where (Link condition) ;
UNION ;
Select A.*, 0.0 as Calc_Amt ;
From A ;
Where (A.Account+A.Aie_Code NOT IN ;
(SELECT B.Account+B.ItemCode FROM B)
INTO AleSum

or What I prefer and is faster on large data sets:

Select A.*, Sum(B.x) as Calc_Amt ;
From A, B ;
Where (Link condition) ;
INTO DBF AleSum

Select A.*, 0.0 as Calc_Amt ;
From A ;
Where (A.Account+A.Aie_Code NOT IN ;
(SELECT B.Account+B.ItemCode FROM ALESUM);
INTO Cursor T1

if _Tally # 0
SELE T1
xDbf=DBF()
SELE AleSum
Append from (xDBF)
ENDIF


HtwH...