Calculate with DISTINTCOUNT doesn't return expected value to calculate Backorders

Hello everybody, I'm just getting started in Power BI and I can't find the way to get an expected result. Hope you can help me.

Let explain the idea, I need to count each time an Extra INVOICE is executed by order. For example in order 1, count 1 backorder. I would like to get the total Grouped By CUSTOMER as shown in the right image. I know the COUNT in BACKORDER match with values, but is not counting that I really need.

The matrix should show 4 where indicated.

I would really appreciate any help, have a nice day.