"I just don't know how to get through to John. My coaching isn't working!" a senior leader exclaimed in frustration to me last week. It seemed like David’s feedback was falling on deaf ears and increasingly John would get defensive when his boss would bring up his skill gaps in delegating to his direct reports. The frustration was mutual and it was starting to impact their working relationship. The reason David's coaching wasn’t working is that he was making some of the common mistakes we all make when trying to change someone's behavior.