So I got a broadcast to help some stalkers out, which I did. when it was done, I heard "come over here stalker, we need to talk". My quest log shows "collect your reward", and points to the guy in charge. But when I talk to him, he doesn't resolve the quest. I tried save/quite/restart/reload, but this is still the situation. He just shows the normal response menu like everyone else does. Is there something I can do to trigger completion of this quest??

I'm using the Gog version on windows 7 64-bit.
No mods except for an "improve the graphics" mod.

Nevermind... I forgot that in CS I need to go back nearby shopkeeper to complete quests, no matter where they originate from. I ask him "you got anything for me?" and that completes the quest.