You probably meant to say, inspired by your answer I decided to use my own approach? :)

Sorry, can not resist :)

Why do you need it in BeforeRolColChange and why you can not use?

local lnRecno, lnValor
select ccheques
lnRecno = recno('cCheques')
sum valor to lnValor for deposita = 1
locate m.lnRecno
thisform.total.Value = m.lnValor

>Hi Naomi
>
>Q.Ok, good. I meant, what is the ControlSource for the column with the checkbox?
>
>Ans.the controlsource of this column is ccheques.deposita, following your instructions I coded the beforerowcolchange event of the grid to scan my cursor, calculate the total, present the sum in another textbox outside the grid and in the end returning to the original recno(). The code is as follows
>
<snip>

>Thanks for all your help
>Luis Santos