Trouble Using Pivot Table off a DNR

[Research RN]

I would like not to have to update the source data for the pivot table in my database. I've read that you can solve this by using a Dynamic Named Range and using that as the source for the pivot table. That way the pivot table will expand as new data is added to the database. The formula I used to create the DNR is:

=OFFSET(Sheet1!$A$1,,,COUNTA(Sheet1!$A:A$),78)

There are 78 columns in the database. And there are 100 rows in the database. However, for some reason, the formula only picks up the first 73 rows in the database. So the formula has to be wrong. But where? How do I get it to pick up all the rows in the database?

Thanks.