How can I make my cinnamon hard candy hotter?

I am making cinnamon hard candy. I finally found cinnamon oil and i thought it was potent, but my candies are not very hot at all. I can barely can taste the cinnamon actually( though it smells highly of cinnamon). The recipe i had found said to add 2-4 drops of the oil I added plenty more than that and its still not where i want it. How much of this stuff do you have to add?