Need help with list.Sum custom colomns

Hello Timo1980 

add a new column and enter this formula. The only thing you have to pay attention is that the variable ChangedType you have to replace with your prior step name.

List.Sum(Table.SelectRows(ChangedType, (sel)=> sel[Customer]=[Customer] and sel[Revenue]>=0)[Revenue])

here the complete code

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUTIEYQOlWB0I1wjEtQBznaBcI1Mw1xnGNYZzdUF8XYi0C4gJMkzXAs4HSVui8AyBimMB", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Customer = _t, QTY = _t, Revenue = _t]),
    ChangedType = Table.TransformColumnTypes(Source,{{"Customer", type text}, {"QTY", Int64.Type}, {"Revenue", Int64.Type}}),
    #"Added Custom" = Table.AddColumn(ChangedType, "Total Revenue", each List.Sum(Table.SelectRows(ChangedType, (sel)=> sel[Customer]=[Customer] and sel[Revenue]>=0)[Revenue])),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "%", each [Revenue]/[Total Revenue],Percentage.Type)
in
    #"Added Custom1"

and here is the output

Copy paste this code to the advanced editor in a new blank query to see how the solution works.

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Have fun

Jimmy