Context Transitioning not working /Code not working

Hi Mkrishna ,

Then you could try EDATE() function. The function returns the date that is the indicated number of months before or after the start date. 

Modified:

Sales Amount =
VAR _Reference_Date =
    MAX ( 'Date'[Date] )
VAR Customers =
    VALUES ( 'Store List'[Store Number] )
VAR PriorCustomers =
    CALCULATETABLE (
        VALUES ( 'Fact Table'[Store Number] ),
        FILTER (
            ALL ( 'Date' ),
            'Date'[Date] >= EDATE ( _Reference_Date, 3 )
                && 'Date'[Date] <= _Reference_Date
        )
    )
VAR CommonCustomers =
    INTERSECT ( Customers, PriorCustomers )
VAR Sales =
    CALCULATE (
        SUM ( 'Fact Table'[Sales] ),
        FILTER (
            ALL ( 'Fact Table' ),
            'Fact Table'[Store Number]
                IN CommonCustomers
                    && 'Fact Table'[Visit Date] >= EDATE ( _Reference_Date, 3 )
                    && 'Fact Table'[Visit Date] <= _Reference_Date
        )
    )
RETURN
    Sales

Best Regards,

Stephen Tao

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