Vader did not sense the force in Leia because at that time she had no awareness of it herself. She had no training in the force. She had never used it. ... The short answer is that creator George Lucas had no idea Leia would end up becoming Darth Vader's daughter.

Why did Vader not check Tatooine?

The theory: Vader would never go to Tatooine because he hates sand. ... Darth Vader HATES sand. He considers it coarse and irritating, and it gets everywhere. [Jedi] know that Darth Vader would never choose to go to a planet covered in sand, and they're right.

Why does Darth Vader recognize c3po?

Darth Vader built C-3PO and spent a lot of time with him from the time of his mother's death to his turn to the dark side. ... Perhaps, Darth Vader just figures that this is another protocol droid and not C-3PO. Obviously, C-3PO does not recognize Vader because his memory was wiped at the end of Revenge of the Sith.