Measure: sumx with summarize

I  have a table with following fields

What I would like to calculate is the additional online sales in case the shop would sell the same % online per product as all shops together. I was able to generate a summarized table that calculates the "additional online sales" 

SummarizedTabel =
ADDCOLUMNS (
    ADDCOLUMNS (
        ADDCOLUMNS (
            SUMMARIZE (
                Sales;
                Sales[Product];
                Sales[Region];
                Sales[Sold by];
                "Sales"; SUM ( Sales[Sales] );
                "Sales Online"; CALCULATE (
                    SUM ( Sales[Sales] );
                    ALLSELECTED ( Sales[Sold by] );
                    Sales[Sold by] = "Online"
                );
                "Sales Store"; CALCULATE (
                    SUM ( Sales[Sales] );
                    ALLSELECTED ( Sales[Sold by] );
                    Sales[Sold by] = "Store"
                );
                "Total shops Online"; CALCULATE (
                    SUM ( Sales[Sales] );
                    ALLSELECTED ( Sales[Sold by]; Sales[Region] );
                    Sales[Sold by] = "Online"
                );
                "Total shops store"; CALCULATE (
                    SUM ( Sales[Sales] );
                    ALLSELECTED ( Sales[Sold by]; Sales[Region] );
                    Sales[Sold by] = "Store"
                )
            );
            "Total shops online vs total"; [Total shops Online] / ( [Total shops Online] + [Total shops store] );
            "Selected shop online vs total"; [Sales Online] / ( [Sales Online] + [Sales Store] )
        );
        "diff total shops vs selected shop"; [Total shops online vs total] - [Selected shop online vs total]
    );
    "additional sales online"; IF (
        [diff total shops vs selected shop] < 0;
        0;
        [Sales] * [diff total shops vs selected shop]
    )
)

But as the original data has more then 1 million rows and I need to apply quite a lot of filters I could like to include the calculation of additional online sales in a measure so that all the report filters get applied (filters based on linked tables). I tried to include the code above in a measure

Addiontional sales =
SUMX (
    ADDCOLUMNS (
        ADDCOLUMNS (
            ADDCOLUMNS (
                SUMMARIZE (
                    Sales;
                    Sales[Product];
                    Sales[Region];
                    Sales[Sold by];
                    "Sales"; SUM ( Sales[Sales] );
                    "Sales Online"; CALCULATE (
                        SUM ( Sales[Sales] );
                        ALLSELECTED ( Sales[Sold by] );
                        Sales[Sold by] = "Online"
                    );
                    "Sales Store"; CALCULATE (
                        SUM ( Sales[Sales] );
                        ALLSELECTED ( Sales[Sold by] );
                        Sales[Sold by] = "Store"
                    );
                    "Total shops Online"; CALCULATE (
                        SUM ( Sales[Sales] );
                        ALLSELECTED ( Sales[Sold by]; Sales[Region] );
                        Sales[Sold by] = "Online"
                    );
                    "Total shops store"; CALCULATE (
                        SUM ( Sales[Sales] );
                        ALLSELECTED ( Sales[Sold by]; Sales[Region] );
                        Sales[Sold by] = "Store"
                    )
                );
                "Total shops online vs total"; [Total shops Online] / ( [Total shops Online] + [Total shops store] );
                "Selected shop online vs total"; [Sales Online] / ( [Sales Online] + [Sales Store] )
            );
            "diff total shops vs selected shop"; [Total shops online vs total] - [Selected shop online vs total]
        );
        "additional sales online"; IF (
            [diff total shops vs selected shop] < 0;
            0;
            [Sales] * [diff total shops vs selected shop]
        )
    );
    [additional sales online]
)

But when I look at the results it is not what I want to see. The total is correct but I am not able to see the additional sales per product en per region.

How can I solve this? Is there another way to get this solved instead of using summarize?

I am using Power BI for just a few weeks, so I would be surprised if there is a much easier way to calculate the additional online sales.

Thanks in advance for your help on this one...

Kind regards

Brenda