Rolling 12 restrict date to less than today, end of the input was reached Issue

[Alpj]

Hi All

I am new to PowerBI and delved around to try and find a solution to prevent rolling 12 charts extending on beyond todays date and pulled together the following, but i am getting an error end of input reached. I have tried changing the parent thesis but for life of me i cannot figure out what i have done wrong. Any help appreciated 

Here is what i have

rolling average =

IF(

    ISFILTERED(DatePast[Date].[Date]),

    ERROR("Time intelligence quick measures can only be grouped or filtered by the Power BI-provided date hierarchy or primary date column."),

    VAR __LAST_DATE = ENDOFMONTH(DatePast[Date].[Date])

    VAR __DATE_PERIOD =

        DATESBETWEEN(

            DatePast[Date].[Date],

            STARTOFMONTH(DATEADD(__LAST_DATE, -11 , MONTH)),

            __LAST_DATE

        )

    RETURN

        IF (

    YEAR ( __LAST_DATE ) IN ALLSELECTED ( 'Calendar'[Year] ),

            AVERAGEX(

                CALCULATETABLE(

                    SUMMARIZE(

                        VALUES(DatePast),

                        DatePast[Date].[Year],

                        DatePast[Date].[QuarterNo],

                        DatePast[Date].[Quarter],

                        DatePast[Date].[MonthNo],

                        DatePast[Date].[Month]

                ),

                __DATE_PERIOD

            ),

            CALCULATE(SUM(opportunity[totalamount_base]), ALL(DatePast[Date].[Day]]))

        )

))))))))))

[amitchandak]

@Alpj ,  Try a measure like

Rolling 12 Sales =
var _max = maxx(allselcted(date),date[date]) // or today()

var _max2 = maxx(allselcted(Sales),Sales[date]) //
var _min = date(year(_max), month(_max)-12,1)
return
CALCULATE(SUM(Sales[Sales Amount]),filter(date, date[date] <=_max && date[date] >=_min && date[date]<=_max2 ))

or

Rolling 12 =

var _max2 = maxx(allselcted(Sales),Sales[date]) //

return

CALCULATE(sum(Sales[Sales Amount]),DATESINPERIOD('Date'[Date ],MAX('Date'[Date ]),-12,MONTH), 'Date'[Date] <= _max2)

[Alpj]

Thank you so much for responding, apologies could you explain this a little,

what is the "allselcted(date)" and "allselcted(Sales)" elements?

am i replacing date[date] with my date range table?

what is the "Sales[date]"?

Fairly new to all this, so would appreciate if you could give a little explanation 

Thank you

Ali

[amitchandak · Accepted solution]

@Alpj , Sorry there was a mistake

use allselected

I trying to get max selected date or max available date in selection from fact- Sales in my case