I have been looking in the forum for the answer to this issue but couldn't get with the answer.
I have a table (let's call it MyTable) with 2 columns: [Values] and [Date].
The graphic I want to make is a simple one: with months as X axis, and in the Y axis the difference between the amount of values on the month of the axis and the amount of values of the same month of the previous year (so I have the variability in %).
I can make a simple measure that counts the amount of values of a certain month, simply using the COUNTA function and filtering the months with the graphic and the year with a slicer, but I couldn't find a way to count the amount of values of the same month of the previous year.
I tried doing that. It gives me an error on the visual, saying "MyTable[Value]: A date column containing duplicate dates was specified in the call to function 'DATEADD'. This is not supported. I don't understand this error... I thought DATEADD was just a movement of the dates 1 year backwards.