Need help with cumulative sum in the back end

[Dave1]

Hi Everyone ,

                                    I am trying to get a cumulative sum  of a table with multiple columns . I was able to achieve this  in front end easily  using this expression RANGESUM (above(total((([  Sales Units] +[Inventory Units])-([Avg Qty]))),0,RowNo(TOTAL)) . But when i am trying to replicate the same thing in script   i am not able to do it . Any help would be greatly Appreciated.

Sample Data :

tab1:
LOAD * INLINE [
  Week,  SalesUnits, Inv units,Avgqty,
    202301, 100, 500, 300
    202302, 500, 0,300
    202303, 600, 0,300
    202304, 700, 0,300
    202305, 900, 0,300
   
];
 

Expected output 

week, Cumulative sum

202301, 300

2020302, 500

2020303,800,

2020304,1200

2020305, 1800

[MarcoWedel]

tab1:
LOAD *,
     RangeSum(SalesUnits+[Inv units]-Avgqty,Peek(CumulativeSum)) as CumulativeSum
INLINE [
    Week, SalesUnits, Inv units, Avgqty
    202301, 100, 500, 300
    202302, 500, 0, 300
    202303, 600, 0, 300
    202304, 700, 0, 300
    202305, 900, 0, 300
];

[Dave1]

It is calculating but getting duplicates for week