Aggregate function Access

Yesterday this code work fine on getting monthly averages

SELECT Avg(turn1.Turn) AS Average, Format([funding date],"yyyy-mm") AS
[Month]
FROM turn1
WHERE turn1.type='Renewal'
GROUP BY Format([funding date],"yyyy-mm");

However I need 'WEIGHTED averages' so
I used this code

SELECT Sum(turn1.[Th Turn]*turn1.[Funding Amount])/Sum(turn1.[Funding
Amount]) AS [WtdAvg], format(turn1.[Funding Date],"yymm") as YYMM
FROM turn1
Where turn1.type = 'Renewal';
GROUP BY format(turn1.[Funding Date],"yymm")
Im getting an aggregate error involving this particular syntax
format(turn1.[Funding Date],"yymm"). any help would be appreciated