Check out this particular tutorial here
There’s actually a bit you need to do and understand to get this working.
It all comes down to understanding the context of the calculation. When you select the date column from the date table it places the specific context over your entire report page. That’s why this can be difficult to solve.
Check out the solution though and you’ll see that this can be done with some unique setup in your data model.
I think you’ll like the functionality of this once you can get it into your report.
Chrs