Using Temporary Columns within Measure

[Anonymous]

Can someone please give me a quick explaination on why I can't use my [NextMonth] in the DateAdd funtion.

EVALUATE
ADDCOLUMNS (
    SUMMARIZE (
        Customers,
        Customers[CustomerKey],
        Customers[DateFirstPurchase],
        "Second Purchase",
            CALCULATE (
                FIRSTDATE ( Sales[OrderDate] ),
                FILTER ( Sales, Sales[OrderDate] > Customers[DateFirstPurchase] )
            ),
        "90 Day Date After First Purchase", Customers[DateFirstPurchase] + 90,
        "NextMonth", ENDOFMONTH ( Customers[DateFirstPurchase] ) + 1
    ),
    "Next3Months", DATEADD ( [NextMonth] , 3, MONTH ),
    "Within 90 Days",
        IF (
            [Second Purchase] > [DateFirstPurchase]
                && [Second Purchase] <= [90 Day Date After First Purchase],
            "Yes",
            "No"
        )

[daXtreme · Accepted solution]