Reporting YTD figures based on user selection

Summary:

Reporting YTD figures based on the user selection

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I have a report where user will select the month/period, so based on the selected month, the YTD figures should also be reported.

I am able to report figures for month based on user selection but not YTD figures.

My source cube is EPBCS, I have enabled dynamic time series and I am able to use substitution variable in Y-T-D(&Month) but not able to figure out any function which can be used to pass POV/user selection to this function. what could be the best approach to report YTD figures for the month based on user selection?