GTKradiant model help

[hotdog321]

hi, i'm trying to make a map using gktradian, i have put some tress and stuff in the game, when i play it i can run straight through the trees and tanks and stuff, how can i make these models solid so that you cant run through it.

[spior]

Well the first thing is make brushes around the tree(the brushes should be the same as the tree).And then textures\common\claulk on all theese brushes.