I can't seem to get the filter for unique records to work. I have a
spreadsheet with about 20 columns and about 3000 rows. I want to filter on
mailing addresses, which is four columns. If I create a
separate worksheet containing data only from the columns I want to filter for
the unique records, and then choose Advanced Filter, and the list range and
criteria range are the same, and click "Unique Records Only", it works. But
if I try to filter the complete worksheet with all 20 columns, and set up the
filtered columns as the criteria and all the columns as the list range, it
just gives me back the same set of rows, including duplicates.

What am I doing wrong?