How can I count distinct values under a same month?

Hi everyone,

I currently have a data set for which I would like to count all unique values that are under a same month and a same year. For example, the following table shows two duplicate values (TR ID's) on two different dates. In this case I would only like to count the unique TR ID's for the month of August, 2020 (which should be 6):

I have been trying to use the =COUNT(DISTINCT(COLLECT(.....))) expression, however, it returns "1", when it should count "6".

Thanks in advance,



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