The Lighting Controller

Hi, another question (sorry to bug you but i'm programming a show and I don'T know everything). 'm having LED par to light up inside a truss. I tried to put it inside but doesn't seem to work. I would like to have a realistic effect when you pu the light inside the truss. Is it possible?

Precisely i'm having 4 light trusses vertical with moving heads on top. I'll put LED cans inside. I would like at least stop the beam light under the moving heads. The light length setup in 3c setup is too long and anyway i'm having 2 lengths of trusses so i don't a general setting. Trusses 1 and 4 is 5 feet and 2-3 3feet.

Thank you all

You can put the light inside the truss, that's easy, I do it all the time in 3D view. However it won't stop the beam from going through the top of the truss from what I can see. Seems to just be a limitation of the engine.