>>Yes, it seems to be global. Also for some reason the NULLDISPLAY property I set for textboxes in the grids columns are ignored. And also
>>
>>I have

sum nI_Dept, nH_Dept, nM_Dept, nO_Dept, nTotal to lnI, lnH, lnM, lnO, lnTotal

>>
>>where all nI_dept are null. But the sum value is 0.00 Why is that?
>
>I think null values are automatically converted to zero for the SUM command, and for the SQL SELECT SUM() function. I don't know about an easy workaround, in case you want to have the sum = NULL (in case one or more of the elements is NULL - this might indicate that data is missing).

Ok, I guess I have to replace 0 with NULL myself :( Also why NULLDISPLAY property is ignored?

It seems to be ignored in grid only. I guess I have to set it myself programmatically.