Change the chart color if...

[#1]

How can I change the "circles" color of my scatter chart if the value of n expression was...

=if(sum(NPS)/count(NPS)>8) Then the color should be Green

=if(sum(NPS)/count(NPS)<6) Then the color should be Red

=if(sum(NPS)/count(NPS)>6<8) then the color should be Gray

I've tried this expression in the Backgound color of my Expression

=if(sum(NPS)/count(NPS)>8,argb(180,0,128,0),if(sum(NPS)/count(NPS)<=6,argb(180,255,0,0),argb(180,128,128,128)))

But it's not working.

So, what is going on?

Thanks for your help

[#2]

I think it's a bug, but the color of the "circle" is not defined in the "Z" axis or in the Dimension axis, but in the "X" axis...