Get Average Monthly BALANCE

On the below data i am trying to get average monthly BALANCE, based on the following query ....but i only getting all records with actual balance and not month wise average balance of the customers......

-----------------------------------
SELECT [customer profit].[Customer Number], AVG ([customer profit].[VAL_BAL]) AS average, Month ([customer profit].[Balance Date])
FROM [customer profit]
GROUP BY [customer profit].[customer Number], [customer profit].[VAL_BAL], [customer profit].[Balance Date];

[Code] .....