Matrix not showing values that aren't matches from related table

[Anonymous]

https://imgur.com/a/UgF5T8e 

Basically what I have is an invoice table and an order table. The tables are linked via a relationship bewteen the order number. When I use the data from the invoice table in a matrix, it does not include the values where there is no order number. The link above is a rudimentary example but basically the same idea. I want to be able to include the negative numbers but since there is no associated order number, they are not being shown in the matrix. Mainly this is due to a slicer from the order table. It can't filter the table if the value doesn't exist in the other. How can I inlcude the missing values?

[kentyler]

Your order table has multiple rows with the ID = 0...this will cause problems. What did you mean by assigning an ID  of 0 ? You need to assign a unique order number to be able to assign orders to invoices.