I'm having an issue with this quest on Belsavis, none of the droids are a viable target for the mind spike. I'm completely lost on how the hell this quest is supposed to work.
As far as I can tell, it's an area quest for The Tomb - http://www.torhead.com/mission/htclEEO#areas
Are you trying the droids in that area? Check your map for a quest radar ping thingy that shows the area. If they're still not working, try logging out and restarting the game, then logging back in.