Default expression should change upon user selection

[Kwame]

Hi guys!

My goal is to set the expression as the default value, but it should also change based on user selection.

This is what I tried, but it didn't work.

Sum({<Location *={'Africa'}>} Sales)

So basically the user needs to be able to get e.g. Sales from other continents by selecting from the location filter and if no selection is made, the expression should return sales for Africa.

[Aditya_Chitale]

if(getselectedcount(Location), Sum(Sales), Sum({<Location ={'Africa'}>} Sales) )

Regards,

Aditya