Hello,

either use:

IF (NVL(curcursor.CURRENT,0) + NVL(tdcursor.thirtydays,0) + NVL(sdcursor.sixtydays,0) + NVL(npcursor.ninetyplus,0) + NVL(custdetail.deposit)) != 0

or exclude NULL's in the first place:

SELECT NVL(SUM(totaldue-totalpaid),0) AS CURRENT FROM tempinvpostless30 INTO CURSOR curcursor WHERE ALLTRIM(custno) == ALLTRIM(scancust.custno)

...

besides this, assuming custno is the tables primary/foreign key
you're better of not using ALLTRIM in the SELECT statements since this isn't optimizable by rushmore

Regards
Christian