VIZ substitution command

[gkoumout]

hey everyone,

so i have brought in CAD linework into VIZ as one layer. these objects that i put into one layer were blocks in CAD. in VIZ i am trying to use the substitution command to replace these objects with trees. i can get to the point where the trees show up on the screen in place of all the CAD objects, which is what i want, and it looks like everything is fine. as soon as i click off of the object though, and go to work on something else, all of the trees and the linework they were linked to disappear. i checked to make sure renderable was on, although i dont think it can be that easy. maybe there is something very obvious i am missing, if you can help that would be great thanks!!!