Conditional Coloring for a Combo Chart

[cmillerclaritas]

All, I have a combo chart displaying sales and % year over year change for a number of products. The products are displayed as bars on the primary measure and the yoy% change on the secondary measure as dots. The bars are colored blue, the dots red. The colors are assigned by Qlik Sense. 

I'm trying to improve the display by getting Qlik to color dots where the YoY % change is greater than zero to be, say, green, and the ones where the yoy% change is negative to be bright red. I don't want to change the bars. Just the dots.

I can't for the life of me figure out how to do this. I've tried defining a master measure with an if statement like if(yoy%change>0, Green(),Red()). I've tried the dialog box but it doesn't seem to let you color the separate measures in the combo box separately through separate expressions. 

I'm attaching a pic and a qvf file to help the discussion. Any thoughts would be much appreciated...

Thanks,

Chris