How did Vader not know?

Sorry if this has already been discussed else where.... but....

How did Vader not know that leia was his daughter from the start?
He is/was after all one of the most powerful Jedi and could sense Obi wan through several tonnes of metal but not his own daughter stood next to him?
Sorry if im being pedantic, but that always puzzled me...

He had felt Obi-Wan before and so recognised his mind.

Leia... he didn't have a clue.

Fair enough.
But she also has Jedi in her (sorry, i refuse to go along with midi-chlorians) so vader should at least have 'felt that?

there are quite a few people who are force sensitive, doesn't mean they are all related to eachother

Yes, and we have seen no clue that you can just 'sense' force awareness- you have to observe it.

i agree with ushgarak on this one. when luke meets kyp durron he has no idea how strong kyp is in the force. it isnt until luke probes him with the force that he feels kyp's power.

Leia is strong in the Force but she wasn't using it at that time and I think that may be more of what Jedi and Sith pick up on, in the PT Jedi require a blood tests to determine how Force sensitive a candidate is, Anakin had to have left Padme when she was still pregnant and later on was led to believe that she and the baby were killed. Later when his son popped up, it never even occured to him that it could have been twins.

i agree with blade on this one.

the amount of midichlorians doesn't make you a better force user

Maybe because they both never would've guessed the possibility?

well he kind of senses the force in Luke at ANH
"The force is strong in this one"

FM always said he found it strange that when Vader said that, OB1 "talked" to Luke

I reject the idea that Vader was sensing 'force power' in Luke with that statement- he was just saying he was being hard to kill, which we would call luck, but he calls the Force. At NO other point can the Force just be sensed like that (like when Vader is face to face with Leia) and the tone of voice he says it in is mere irritation, not astonishment.

No, I see no evidence that you can just automatically feel someone's force strength.

but you can feel disturbances in the force, right? other than alderaan being destroyed, what qualifies as a disturbance in the force?

Well, my impression is that Luke was using the force at that moment and thats why Vader said what he said. As mentioned earler in this thread they (vader and palpy) are able to sence a disturbance in the force.

so luke being trained by obi wan caused a disturbance, which palpantine and vader picked up on.....

maybe

remember in ep.5...emperor"theres has been a disturbance in the force"...vader"i have felt it master".....emperor"we have a new enemy, luke skywalker"