why is this not working?

with t1 as
(select Sale_Day, Item_ID,
       SUM(rate * quantity) Total,
       row_number() OVER(partition by Sale_Day
       ORDER BY SUM(rate*Quantity) desc) as rn
  FROM scratch
 GROUP BY Item_ID, rate, quantity, Sale_Day)

 --select * FROM scratch

select Sale_Day, Item_ID, Total
from t1
WHERE rn = 1
ORDER BY Sale_Day