"I taught my dog to whistle"
"I can't hear him whistling"
"I said I taught him. I didn't say he learned it"
(from David Minton)
Just because you've done a presentation doesn't mean you have changed the audience. Did you think about what the audience wanted and why they should bother learning to whistle? Too many people present without thinking it through from the audience's point of view. How does it affect their lives? Why should they bother to learn this new skill? What part of the presentation grabbed them?
Think audience, audience audience or you'll end up barking up the wrong tree.