How many Skywalkers can there be???
So that dialogue between Vader and the Emperor in ESB was to establish that Vader had no clue Luke was his son, right? Basically I get the impression Anakin wil believe the baby is dead when he is dueling with Obi-Wan.
If that's the case...and we are supposed to believe Vader does not recognize Luke Skywalker is his son, until the Emperor tells him so, why the following:
The opening crawl says Vader is searching for Luke
Vader wants Skywalker brought to him (Skywalker is on that ship)
Dude...how many Skywalkers can possibly be in the galaxy?