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

The above line is used in a form that can contain null results. I can't see that I have changed anything, but if any of these are null, the line evaluates to zero. I would like it to be the total of the numbers in all of the cursors treating nulls as zero. Any ideas? The cursors are populated by these statements:

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

SELECT SUM(totaldue-totalpaid) AS thirtydays FROM tempinvpostthirty INTO CURSOR tdcursor WHERE ALLTRIM(custno) == ALLTRIM(scancust.custno)

SELECT SUM(totaldue-totalpaid) AS sixtydays FROM tempinvpostsixty INTO CURSOR sdcursor WHERE ALLTRIM(custno) == ALLTRIM(scancust.custno)

SELECT SUM(totaldue-totalpaid) AS ninetyplus FROM tempinvpostninety INTO CURSOR npcursor WHERE ALLTRIM(custno) == ALLTRIM(scancust.custno)

The applicaiton at one point ran under VFP7 and was upgraded to VFP8 and recently VFP9. I do have a SET ENGINEBEHAVIOR 80 active. I am pretty sure that it worked under 9.0, so I am not sure what changed. Please help...

Randy Wessels