How to solve a SQL problem?

Question

SQL

task description:
The database table contains the following columns:
Sales(Date, ProdID, OrderID, ManagerID, Sum)
Write an SQL query that will show the manager with the highest sales for specific orders in 2019 (by months).
The query must return the Month, Manager (ManagerID), Order Numbers (OrderID) and Sum.

My decision:

SELECT MONTH(DATE), ManagerID AS Менеджер, OrderID AS Номера заказов, max(Sum)  AS Сумма
FROM Sales
WHERE Sum = max(Sum) and YEAR(DATE) = 2019;

How to fix the request so that it works correctly?