I was always told it's rude to point . . .
Seriously, though, I really don't think this one is a big deal. When he looks at an object and whines, do you automatically get it for him? Or do you point at it and then get it for him? That might help. But, really, it's kind of an arbitrary milestone, I think. I mean, when he's 20 years old, no one's going to say "so, when did you learn how to point?" Every kid is different and I'd bet your ds has some skills other 20 mo toddlers don't have, anyways. Pointing is probably just not a priority.