I think the reason why measure doesn't work is that when the data comes from two tables, you can't directly use the selectedvalue() to get and compare them. Generally speaking, we usually use the key between the two tables and then filter to get the corresponding row, and then compare. Can you share some sample data so I can investigate further. Thanks.
Community Support Team _Tang
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Unfortunately your formula does not work. I get message that "column Sales office country]])=Max('IObOL new (incl K Group)'[Country name was not found in table "salesoffices" or is not being allowed to be used in this term...