I have a turf which is the bush of a tree, I put it on the map above my base icon which is turf = /turf/grass so the map if filled with grass the icon doesnt use up its whole 32x32 square so the top part is empty and hence meant to be transparent i put it on the map on top of my grass and the part thats meant to be see through is black

turf
top
icon = 'Tree.dmi'
layer = MOB_LAYER+1

this is the code ive used to put it above the player the player walks behind the bush, but is on top of the black area which should be see through revealing the bass grass turf on the bottom but instead is black?

anyone have any suggestions why this is happening?