SUM OF DIFFERENCES - DAX FORMULA

[Zbig62]

Hello everyone and please help

MY PROBLEM

In the table "TABLE1" I have the values ​​"id" and "Value". The measure "Value n-1" calculates the value from the previous row of the table. The column "Differ" is a measure that calculates the difference between "Value" and "Value n-1". At the level of a single row in the table, everything is calculated correctly. However, I need to calculate the sum of differences from the column "Differ". The calculated value in the table "Table1" should be "10" but it is "37". The problem probably lies in the lack of a sum of values ​​for the column "Value n-1". What am I doing wrong? Please help

Value n-1 =

var a =

 CALCULATE(

    max(TABLE1[id]);

    FILTER(

        ALLSELECTED(TABLE1[id]);TABLE1[id] < SELECTEDVALUE(TABLE1[id])

    )

 )

 RETURN

  CALCULATE(

    SUMX(TABLE1;TABLE1[Value]);TABLE1[id] = a

 )

Differ =

var a = TABLE1[Value n-1]

RETURN

   sumx(TABLE1;TABLE1[Value] - a)

[DataInsights · Accepted solution]

@Zbig62,

Try these measures:

Sum of Value = SUM ( Table1[Value] )

Value n-1 = 
CALCULATE (
    [Sum of Value],
    OFFSET ( -1, ALLSELECTED ( Table1[id] ), ORDERBY ( Table1[id], ASC ) )
)

Differ = [Sum of Value] - [Value n-1]

[Zbig62]

Thank you very much for your support
everything works fine