Collidable grass problem in RBR

[dika]

I created a track with BTB for RBR. If i put some grass (from GB pack or Poland pack) on my track, in the game i collide with it, when i hit it. It was the same when i selected driviable or moveable or only render. Everytime the same failure after export into the game. Wat can i do, or where is my failure? I found a lot of tracks here where it works propper. Can anybody help me????

dika