Comparing columns error

Hi Necrosis1968 ,

According to your statement, I think your error may be caused that you use 'report this month'[Unique ID] directly in your code to create the calculated column.

This error occurs because Power BI is unable to determine which row of data to use in a calculation among multiple rows of data.

Here I create a sample and I can reproduce your issue.

Last Month:

This Month:

Error:

I suggest you to try code as below.

Resolved = IF ('report last month'[Unique ID] in  VALUES('report this month'[Unique ID]), "No", "Yes")

Result is as below.

Best Regards,
Rico Zhou

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