C# Not Supported?

我有以下...

using System;
using System.Management;
using System.Windows.Forms;
namespace WMISample
{
    public class CallWMIMethod
    {
        public static ushort GetMonitorBrightness() {
            using (var mclass = new ManagementClass("WmiMonitorBrightness")) {
                mclass.Scope = new ManagementScope(@"''.'root'wmi");
                using (var instances = mclass.GetInstances()) {
                    foreach (ManagementObject instance in instances) {
                        return (byte) instance.GetPropertyValue("CurrentBrightness");
                    }
                }
            }
            return 0;
        }
        public static void SetMonitorBrightness(ushort brightness) {
            using (var mclass = new ManagementClass("WmiMonitorBrightnessMethods")) {
                mclass.Scope = new ManagementScope(@"''.'root'wmi");
                using (var instances = mclass.GetInstances()) {
                    foreach (ManagementObject instance in instances) {
                        object[] args = new object[] { 1, brightness };
                        instance.InvokeMethod("WmiSetBrightness", args);
                    }
                }
            }
        }
        public static void Main()
        {
            Console.WriteLine (GetMonitorBrightness());
        }
    }
}

这是使用 WMI 获取显示器亮度的非常基本的事情。但我似乎无法运行它，我一直在foreach (ManagementObject instance in instances) {收到关于System.Management.ManagementException - Not supported的错误，我不确定发生了什么。我正在使用 monodevelopment 来编译它。它编译正常，只是在尝试运行时死亡。我使用的是Windows 7，所以不是那样。WMI 服务正在运行。

我不确定发生了什么。