Where are you entering this formula?
Am I right in saying that you want the date to be transferred to a table? If so, you'll have to set the Form's Recordsource to be the specific table, and then set the control's ControlSource to be a field in that table. Then use the DefaultValue of the control to put your formula in.
Also, are you sure you want to use Now() to get the date? This will return, for example, 29/01/02 12:05:37 . You might want to consider just using =Date() if you are only interested in the date.