12 months values are not returned based on the date period slicer

[tek01]

I have a DAX that was suppose to return values based on date period slicer but returns blank.
The scenario is I have a date table and a dateDup table which are not related. They both contain all dates and MonthYear fields and the values are Apr-2023, May-2023 and so on. Another fields has PeriodmonthYear and the values are P1 Apr-23, P2 May-23 and so on. And aslo a financial Year e.g. FY 2022/23, FY 2023/24 etc.

I want to create a line chart that when Financial slicer is selected, let say FY 2023/24 and PeriodMonthYear slicer is selected, let say P1 Apr-23 then the line chart should return the last 12 months sum of Actual Target. i.e values from P12 Mar-22 to P1 Apr-23. And if i select P2 May-23, it should return line chart with P1 Apr-22 to P2 May-23

hence, the Dax i used is 

Actual S4 | Last 12 Months = 
var _sum = SUM('KT Targets Scenarios'[Actual S4 Stretch met])
var maxdate = MAX(DateTable[Date])
var maxdate_12MonthsAgo = EOMONTH(maxdate, -12)
var Result = 
    IF(
        HASONEVALUE( DateTableDup[Month Year] ) && 
            MAX( DateTableDup[Date])  <= maxdate &&
            MIN( DateTableDup[Date]) > maxdate_12MonthsAgo ,
        CALCULATE(_sum, 
            FILTER( ALL(DateTable[Period_MonthYear]),
                DateTable[Period_MonthYear] = Values( DateTableDup[Period_MonthYear]) 
                )
        ),
        BLANK()
    )
return 
Result

This is returning blank.
Note my datetables are not related.
When I add Company slicer and select All, then is wasn't blank but show all values from the 12 months but same values see below screenshot.

This is wrong. please how can i get dax working well.
I need your help.

[amitchandak · Accepted solution]

@tek01 , when you select one value, and want to display more than that, you need a slicer on the independent table(Date table here) 

//Date1 is independent Date table, Date is joined with Table
new measure =
var _max = maxx(allselected(Date1),Date1[Date])
var _min = eomonth(_max, -12) +1
return
calculate( sum(Table[Value]), filter('Date', 'Date'[Date] >=_min && 'Date'[Date] <=_max))

Need of an Independent Date Table:https://www.youtube.com/watch?v=44fGGmg9fHI