请问任何修改vista的时间

修改WIN32的时间可以如下实现。可是在vista下没有用啊
   /// <summary>
    ///系统时间类
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    public class SystemTime
    {
        public ushort year;
        public ushort month;
        public ushort dayofweek;
        public ushort day;
        public ushort hour;
        public ushort minute;
        public ushort second;
        public ushort milliseconds;
    }    /// <summary>
    /// Windows API方法
    /// </summary>
    public class Win32API
    {
        [DllImport("kernel32.dll")]
        private static extern Boolean SetSystemTime([In, Out] SystemTime st);        /// <summary>
        /// 设置系统时间
        /// </summary>
        /// <param name="newdatetime">新时间</param>
        /// <returns></returns>
        public static bool SetSysTime(DateTime newdatetime)
        {
            SystemTime st = new SystemTime();
            st.year = Convert.ToUInt16(newdatetime.Year);
            st.month = Convert.ToUInt16(newdatetime.Month);
            st.day = Convert.ToUInt16(newdatetime.Day);
            st.dayofweek = Convert.ToUInt16(newdatetime.DayOfWeek);
            st.hour = Convert.ToUInt16(newdatetime.Hour - TimeZone.CurrentTimeZone.GetUtcOffset(new DateTime(2001, 09, 01)).Hours);
            st.minute = Convert.ToUInt16(newdatetime.Minute);
            st.second = Convert.ToUInt16(newdatetime.Second);
            st.milliseconds = Convert.ToUInt16(newdatetime.Millisecond);
            return SetSystemTime(st);
        }    }