Read the error message? You need to have at least 1 instance of the drop in a layout for construct 2 to know what it should be like.
I want a, when i click on CanDo, Money substract -5, Tower1 spawn on CanDo.X CanDo.Y, CanDo destroy, but i have same CanDo and i don't know how instanse show the object, i mean i don't understand how i can do this