ontime()线程间操作无效从不是创建控件""的线程访问它

问题：ontime()线程间操作无效从不是创建控件""的线程访问它代码为：
  public Form1()
        {
            InitializeComponent();
            InitializeTimer();
          //  InitializeNotifyMenu();
        }   public void InitializeTimer()
        {
            this.timerClock.Elapsed += new ElapsedEventHandler(OnTimer);
            this.timerClock.Interval = 200;
            this.timerClock.Enabled = true;        }
      public void OnTimer(Object source, ElapsedEventArgs e)
        {
           
                this.clockTime++;                int countDown = this.alarmTime - this.clockTime;
                timeInput.Text = secondsToTime(countDown);
       }
     
       public string secondsToTime(int seconds)
        {
            int minutes = 0;
            int hours = 0;            while (seconds >= 60)
            {
                minutes += 1;
                seconds -= 60;
            }
            while (minutes >= 60)
            {
                hours += 1;
                minutes -= 60;
            }            string strHours = hours.ToString();
            string strMinutes = minutes.ToString();
            string strSeconds = seconds.ToString();            if (strHours.Length < 1) strHours = "0" + strHours;
            if (strMinutes.Length < 1) strMinutes = "0" + strMinutes;
            if (strSeconds.Length < 1) strSeconds = "0" + strSeconds;           return strHours + ":" + strMinutes + ":" + strSeconds;
        }
代码运行时发生了ontime()线程间操作无效从不是创建控件""的线程访问它。我的解决方法为：
 public void OnTimer(Object source, ElapsedEventArgs e)
        {
           
                this.clockTime++;                int countDown = this.alarmTime - this.clockTime;
                timeInput.Text = secondsToTime(countDown);
                if (timeInput.InvokeRequired == true)
                {                    timeInput.Invoke(source, new object[] { Text });这儿就老不对。
                }
                else
                {
                    timeInput.Text = "";
                }