Using MSOffice 2003

I have a ws named lists. Col A has my list that I am using in the data
validation technique to get drop boxes on my working spreadsheet. It is
working well as is, but I want the user to be able to add to the list.

When I add an item thru the drop box, it does not get added to the
column in the Lists ws.

I do have error alert unchecked in the data validation dialog box.

Here is my syntax for making the list dynamic - I suspect something is
incorrect here, but don't know what it is.

=OFFSET(Lists!$A$1,0,0,COUNTA(Lists!$A:$A),1)

Thanks for your time
Joanne