How often do we drag or push our horses somewhere? How often are they truly yielding from a feel?
As humans we are prone to predatory behavior and being hand oriented. It is easy for us to push, crank, yank, and leverage our way to getting what we want. All the more reason it is so important to remember that our prey animal partners are so sensitive and perceptive that if we are having to make our horses yield to a feel then our communication is broken.
It's likely one of two things that is causing your horse not to follow the feel you are offering - he's scared or he's disrespectful (and/or your timing on the release is poor).
Check out this excellent video from 3-Star Parelli Professional Jake Biernbaum on simulating offering your horse a good feel. Developing a great Porcupine Game will enhance the horse's respect for you and build confidence in your leadership.
Remember, the Porcupine Game is the second game for a reason, it helps you win the horse's mind.