the turret is always visible

my game involves several turrets. i have the turretControl script from the tornado twins tutorials. but my problem is that when i'm playing the game, my turrets are always visible, through the trees and visible from a very long distance.

i want it so that when you play, 1, you cant see a turret that is half a terrain length (100 unity units) away. 2, you cant completely see a turret that is behind a tree.

please help me anyone!

well just try to change the layer

is it on default or blank.... if its blank set it to default it should then work

hope that helps