Secondary axis in a combo chart not working properly

Hello, 

I have the combo graph that you see below and I added a secondary axis on the right of it. The issue that I have is that I am not able link an excedance factor to the hight of the different regions in the secondary axis. 

For example for the developed country column height I want to assign a value 24,7 in the secondary axis; however when I add that value, excel creates a new column with that hight (the yellow one)  instead of linking it to the value of the developed country column, any suggestions on how to link the hight of the columns with a secondary axis?