Discuss issues first, ideas and solutions later.
During your meetings with the middle manager you lead, I would focus on the issues and problems that exist in their team. Ask questions and listen actively. Try to direct the conversation into the areas you believe require his attention, to see if they are aware of the issues himself. Ask what they intend to do in this particular situation, leave advice for later stage.
Sometimes an important issue really goes over their head. In that case, address the matter directly ("I noticed that recently..."), and again ask what they intend to do and how their plan will make the situation better. Get back to them about the issue frequently, let them describe the steps they took and how the situation improved. If the issue fails to improve, reiterate the importance of the subject matter to you. You're the manager, you set priorities.
Ultimately, you are his supervisor. In this case, the line between "advice" and "instruction" is quite thin. Don't forget that as a manager you have to sometimes cross the line to address more important issues, if your middle manager fails to do so. Use your intuition and approach each situation individually.