>OK
>I changed my cursor (record source for the grid) to numeric and I added 'not null'.
>I continue to see the null even I press on my 'Mark All' command button with this code:

select crsrgrid
>	replace all crsrgrid.tochange with 1
>thisform.cmlaborig.refresh()
>thisform.calcsum()

Hmmm probably that cursor is not the source for grid. Try:

select (thisform.cmlaborig.Recordsource)
replace all tochange with 1

Cetin