Can't sum (measure) selected parameters

Hello,

Need some help here.

I need to calculate top 10 Account Receivables amounts based on user selection.

For that, I created the below What-if Parameters and used it for "Selectable" Ranking (rank amounts from top to lowest value).

What-if Parameters

I created another measure to calculate Sum of Amount which users can select ranking (say top 10 amounts).

Rank (measure)

The result

However, when I tried to Sum "only selected Parameter" (say only sums top 10 AR), my measure is not working.

Not sure if this is a Power BI issue or my DAX is wrong.

My data structure:

Any help will be appreciated. Thanks in advance.