Rolling Avg for Last 21 days - powerbi

Question

How can I create a measure to calculate the avg spend for the last 21 days? My formula below returns a null
Average of Spend rolling average =
VAR __LAST_DATE = LASTDATE('Raw_Data'[Date_1].[Day])
RETURN
AVERAGEX(
DATESBETWEEN(
'Raw_Data'[Date_1].[Day],
DATEADD(__LAST_DATE, -21, DAY),
DATEADD(__LAST_DATE, 0, DAY)
),
CALCULATE(AVERAGE('Raw_Data'[Spend]))
)
I can't generate a value. It returns a 0

Answer 1

Other than using [Date_1].[Day] and an off-by-one error with DATESBETWEEN that looks fine. eg this
Average of Spend rolling average =
VAR __LAST_DATE = LASTDATE('Raw_Data'[Date_1])
RETURN
AVERAGEX(
DATESBETWEEN(
'Raw_Data'[Date_1],
DATEADD(__LAST_DATE, -20, DAY),
DATEADD(__LAST_DATE, 0, DAY)
),
CALCULATE(AVERAGE('Raw_Data'[Spend]))
)
Appears to work correctly for me with
let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjIwMtI1MAQiJR0lU6VYHSQhI6CQoQGqmDFQzBhNzASkFU3MFKwXKBgLAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date_1 = _t, Spend = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Date_1", type date}, {"Spend", Int64.Type}})
in
#"Changed Type"