Why the property of the class implementing the interface not working?

Kindly, i need to know what i am missing or what i am doing wrong with the following code?

public class Program
{
    public static void Main()
    {
        var a = new A();
        a.Controls.Add(new B());
        a.Controls.Add(new C());
        a.Controls.Add(new D());
        a.DisplayMode = DisplayMode.Edit;
    }
}
public enum DisplayMode
{
    View = 0,
    Edit = 1
}

public interface IMode
{
    DisplayMode DisplayMode { get; set; }
}

public class A
{
    private DisplayMode mDisplayMode;
    public A()
    {
        mDisplayMode = DisplayMode.View;
        Controls = new List<object>();
    }
    public DisplayMode DisplayMode
    {
        get
        {
            return mDisplayMode;
        }
        set
        {
            if (mDisplayMode != value)
            {
                mDisplayMode = value;
                foreach (var control in Controls)
                    if (control is IMode)
                        (control as IMode).DisplayMode = value;
                // the control ( b ).DisplayMode is not firing or executing the set
                // what i am missing here?
            }
        }
    }
    public List<object> Controls { get; set; }
}

public class B : IMode
{
    private DisplayMode mDisplayMode;
    public B()
    {
        X=0;
        mDisplayMode=DisplayMode.View;
    }

    public int X { get ; set;}

    public DisplayMode DisplayMode
    {
        get
        {
            return mDisplayMode;
        }
        set
        {
            if (mDisplayMode != value)
            {
                mDisplayMode = value;
                // some code should be executed;
                X=10;
            }
        }
    }
}

public class C {}

public class D {}

after i call a.DisplayMode=DisplayMode.Edit i am expecting that all controls ( B ) will execute the set of DisplayMode, but after executing the code, its not firing at all

what i mean by the DisplayMode setter value is not executing because if so then X value should become 10