however, the family connection is still pretty solid. like said, vader could sense luke when palpatine could not...possible do the the family connection and the fact that Vader was more actively searching for him that palpatine was. When luke called out to leia he did so as a man hanging from under a city with no arm...it wasnt like he was really expecting (at least not conscously) her to respond. But due to the family connection she did 'hear' him. Chaltab's comment could explain why vader didnt know leia was his daughter (plus from what we know, Lucas didnt decide that until at least after ANH
) but i am totally confused as to how/why he brought Padme into it...it was never said/suggested that she had any linking to the force (well im sure there are things that you can say suggest it, but it was never said)now, people have said why couldnt the Jedi sense palps and even anakin's evilness (which that part at least is still yet to be seen so we cant really comment on it) well like was said, the Dark Side clouds everything...and they are able to mask/hide themselves from the jedi....but thats not exclusive...just cause Vader or Palpatine is clouding the force and hiding their precense doesnt in anyway mean that they cant still sense Jedi (remember, vader sensed Obi-Wan, Obi-Wan never sensed vader)
-Darth Simon