I chuckled to myself. That's about right. In the trenches, a solution is what you hang, not what you find to take to your manager. A nurse in the trenches goes to her manager with problems. She enters with problems. She leaves with solutions. At least she does if her manager is doing their job.
While it is nice to have your staff bring you solutions to their problems for you to implement, hanging such a sign on your door is tantamount to hanging a sign reading "Take Your Problems Elsewhere." That definitely sends the wrong message to your staff.