How to count records in a range dates per month

Hi, MaNUEL2019 

Firstly, you can create a calculated table as follows.

Dates = CalendarAuto()

Secondly, you may create two columns and a measure as below.

FormatDate = FORMAT([Date],"MMM") & "-" & FORMAT('Dates'[Date],"YY")

Machines = "Machines"

Amount =

CALCULATE (

    DISTINCTCOUNT ( 'Table'[machine Serial number] ),

    FILTER (

        FILTER(ALLSELECTED ( 'Table' ),'Table'[Customer] IN FILTERS ( 'Table'[Customer] )),

        OR (

            [Init date] <= MAX ( 'Dates'[Date] )

                && ISBLANK ( 'Table'[End date] ),

            NOT (

                OR ( [Init date] >= MAX ( 'Dates'[Date] ), [End date] <= MIN ( 'Dates'[Date] ) )

            )   

        )

    )

)

Result:

If I misunderstand your thought, please show me your expected output. I am glad to solve the problem.

Best Regards,

Allan

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