I don't know what happened, but suddenly Davik was dead and Calo was killed by debree.
I'm on Dantooine now, but there's a new problem/question:
I've completed the main quest: investigate the ruins, but I still can't get off the planet, to head for Tatooine (i checked walktroughs). Do I have to complete all side-quests before I can leave?
Thanks for the help