Expectations.

Are you clear about them with your employees? Does your boss know what you expect from him/her? There is a saying that "Expectations are premeditated resentment." How many times a day do you think someone knows what you want? Be clear and concise. It is the little things that we don't communicate to each other that gets us in trouble with each other. If you want an employee to stay late, tell him/her early in the day and explain the reason. If you can't stay late and your boss asks you, explain the reason and offer a solution. Can you get the work done just not right after the 'regular" hours but later in the evening?
Respond to the non verbal signs you get when explaining something. You see the signs but in your rush to get your point across, you may ignore the signs. Take time now and save time later.