Pedro,

Move your code into Valid() of checkbox and change RETURN .F. to RETURN 0.

>Hi
>
>in one form , i need show status of one field .
>Field is .T. , or .F. = "Close" or "Open"
>
>I use one CheckBox style graphical .
>
>End user can change status .
>
>I want when end user click in CheckBox style graphical , the VFP show one message ask if he is sure about it .
>
>I have this code in When , checkBox graphical , but don´t work .
>
>Can you help me ?
>
>Thanks
>
>

>
>** code when
>
> IF EnCab.fechada = .F.
>
>  cMessageTitle = 'Stop'
>  cMessageText = 'Do you want close ... ?'
>  nDialogType = 4 + 32 + 256
>
> ELSE
>
>  cMessageTitle = 'Stop'
>  cMessageText = 'Do you want open ... ?'
>  nDialogType = 4 + 32 + 256
>
>
> ENDIF
>
>
> nAnswer = MESSAGEBOX(cMessageText, nDialogType, cMessageTitle)
>
> IF nAnswer = 7
>
>  RETURN .F.
>
> ELSE
>
>  RETURN .T.
>
> ENDIF
>
>