Cumaltive Diff with missing days

Hello DonalMc 

try thid DAX code

Usage =

VAR currentDate = 'ESB Data'[Date]

VAR currentType = 'ESB Data'[Type]

VAR previousDate =

    CALCULATE(

        MAX('ESB Data'[Date]),

        FILTER(

            ALL('ESB Data'),

            'ESB Data'[Date] < currentDate &&

            'ESB Data'[Type] = currentType

        )

    )

VAR previousReading =

    CALCULATE(

        SUM('ESB Data'[Reading]),

        FILTER(

            ALL('ESB Data'),

            'ESB Data'[Date] = previousDate &&

            'ESB Data'[Type] = currentType

        )

    )

RETURN

    IF(

        NOT ISBLANK(previousReading),

        'ESB Data'[Reading] - previousReading,

        BLANK()

    )

Thanks,
 Pankaj Namekar | LinkedIn

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