Hi @NathanPzi ,
If the relationship is one to many, RELATED function can only be used in the many side table. In other words, 'Grille tarifaire' should be the one side in the relationship.
If not, you can use this formula to reference:
MAXX ( FILTER ( 'table2', 'table2'[column1] = 'table1'[column1] ), [column2] )
Community Support Team_yanjiang
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