Stuck on a quest (S.T.A.L.K.E.R.: Shadow of Chernobyl)

I decided to try mod Call of Chernobyl by stason174 v.6.03 was going so well liked and that's the problem at the beginning of the game.Can't find the Part of the Brain Burner.In the place where it should be is the tree so it is certainly underground.I near climbed and brought me to the lab X18.I thought well, then she or her gets to her.All her searched, but nothing o__o Where did she get to it?