Well, in your 3MB pic, I see you have 2 local minimuns.
Change your graph to Lines and Bars.
You may create a new expression in a bar expression and show only a determinate point.
If(Value = max(Value), Value) or something like that.
You may have to aggregate this funcktion on the dimension or dimensions required.
To get the second max(Value), exclude from the expression the first max. It's that possible?
Go to Object Properties.
You'll see different graphics. Chose the one showing lines and bars. In the Expressions tab, select your 2nd expression and check bars, uncheck lines.
- Set your 2nd expression as If(sum(Value)=aggr(Max(sum(Value)),Date), sum(Value), null()) à Something like that
You’ll see a bar only in the correct date.