scrolling to bttom of table not working

trying to get datatables to scroll to the bottom row.

my code:

        transactions_table.on('draw', function () {
            var num_rows = transactions_table.data().length;
            //transactions_table.scroller.toPosition(num_rows - 1);
            transactions_table.row(num_rows - 1).scrollTo();
        });

I have tried either of the 2 lines toposition() and scrollto() and neither works, the table just stays at the top row.

paging, searching, ordering, info are all set to false.

I have tried replacing the "num_rows-1" with just the number 100, still no scroll.

The num_rows variable does get set to the correct # of rows in the data, so the issue is with the scrolling.

Not sure what I'm missing.

Thanks