Thank you for your sharing.
After I play round your script , it work fine. Since my condition is only 2 :-
GP % > 30 % yellow
GP % < 20 % Red
GP % between 20 % to 30 % Green
It is possible for you modify the expression to allow me enter only 2 value .
As now your script allow me enter 3 value.
Sent from my iPhone
For the bar chart left axis is there and for the line chart right axis is there in your report.
Now you want the bar chart has to reflect on right axis basis. do you have any relation between
bar & line chart if yes then it will be easy to write the back ground color condition.