Change the color of a line in a combo chart according to an expression.

I have two trend lines - say actuals and target - which are to be added to a vizlib combo chart. I want to change the color of the actuals line to red when it goes above the target line, and green when it crosses downwards. So essentially the color of the actuals line will be red when it is above the target and green when it is below the target.  I added an expression in the line color settings of the actuals measure
=if(Sum({<OverDue={'Yes'}>}$(Value_EUR_LC))>Sum(AOP),LightRed(),LightGreen())
but it does not work and changes the color of whole line to LightGreen.
The persistent color is turned off and the color is set to auto  

Can anyone help.