thats strange , i'm pretty sure any material would smoke under those conditions
its most likely your tobacco , (my selfmade tobacco doesn't smoke either unless i add a cola-sirop smoke liquid and honey)
try adding , hookah-honey or regular honey (just a little bit if regular)
then fold a bit of foil untill its thick , cut it so it becomes like a "grill"
put it direct on the tobacco , and put your coal on top of it....
(thats how i smoke self-made tobacco...)
Although this usually has a bad effect on the regular tobacco , you might wanna try it