Absolute Cumulative Graph

Hi
I have the following data 

And with a measure i need to create the following absolute cumulative graph



the graph show the cumulative column by type and month. The cumulative column is the absolute value of Real - Plan for each type

Im Using this measure to create the Absolute column of Real - Plan

ABS Real-Plan = 
abs(CALCULATE ( SUM ( Table[Amount] ); Table[PoR] = "Real" )
    - CALCULATE ( SUM ( Table[Amount] ); Table[PoR] = "Plan" ))

and im using this measure for the cumulative column that i'm graphing

Cumulative = 
CALCULATE (
    SUMX (Table; [ABS Real-Plan] );
    FILTER ( ALLSELECTED ( Table[Month] ); Table[Month] <= MAX ( Table[Month] ) )

but i'm getting a strange results in the grad total on the table and in the graphs numbers. EXAMPLE for type A




Thanks