It is impossible to get the job (S.T.A.L.K.E.R.: Clear Sky)

Hi! The problem is this: go to a location in Dark valley, the mission to talk to the commander of the checkpoint, nothing new, everyone knows everything. Only one to put the gun down does not speak, zero attention. Red mark is the story of the quest is lit, if you press Tab also displays the job. You can not talk with all, one does not speak, even there is no inscription to Say when suitable. Reached the place where the detachment of Freedom killed, to shoot there dogs, nothing has changed. Reached the base of Liberty, the mission is over, a new task is to find the Commandant, or something like that. The gate to the hangar are closed, not a soul on the basis of no. Version 1.5.10, is the ruler of the gold zone, the pumping arms and armor in all branches, fixed faction wars. Game reinstalled, did not help. If anyone was, please share your advice on how to fix it.