线程参数问题

code=C#] private void DrawTimer(Graphics g)
        {
            //画时钟外表
            
            for (double k = 0; k <= 360; k += 6)
            {
                d = (double)(k * Math.PI / 180);
                float x1 = (float)(160 * Math.Sin(d) + 200);
                float y1 = (float)(200 - 160 * Math.Cos(d));
                if (k % 30 == 0)
                {
                    g.FillEllipse(new SolidBrush(Color.Green), x1 - 5, y1 - 5, 10, 10);
                }
                else
                {
                    g.FillEllipse(new SolidBrush(Color.Red), x1 - 5, y1 - 5, 5, 5);
                }
            }
            while (true)
            {
                degree = (double)(s * Math.PI / 30);
                if (true)
                {
                    //秒针
                    float x = (float)(150 * Math.Sin(degree) + 200);
                    float y = (float)(200 - 150 * Math.Cos(degree));
                    g.DrawLine(new Pen(Color.Blue), new Point(200, 200), new PointF(x, y));                    //分针                    
                    mX = (float)(130 * Math.Sin(mdegree) + 200);
                    mY = (float)(200 - 130 * Math.Cos(mdegree));
                    g.DrawLine(new Pen(Color.Red, 2), new Point(200, 200), new PointF(mX, mY));
                    mdegree += (float)(1 * Math.PI / 1800);                    //画时针
                    hX = (float)(120 * Math.Sin(hdegree) + 200);
                    hY = (float)(200 - 120 * Math.Cos(hdegree));
                    g.DrawLine(new Pen(Color.Gold, 3), new Point(200, 200), new PointF(hX, hY));
                    hdegree += (float)(1 * Math.PI / 21600);                    System.Threading.Thread.Sleep(1000);
                    g.DrawLine(new Pen(myForm.BackColor), new Point(200, 200), new PointF(x, y));
                    g.DrawLine(new Pen(myForm.BackColor, 2), new Point(200, 200), new PointF(mX, mY));
                    g.DrawLine(new Pen(myForm.BackColor, 3), new Point(200, 200), new PointF(hX, hY));
                }
                s = Convert.ToInt32(DateTime.Now.Second.ToString());
            }
        }[[/code]
该方法在Timer类中实现
在主程序用
Graphics g = e.Graphics;
            Timer myTimer = new Timer();
            ThreadPool.QueueUserWorkItem(new WaitCallback(myTimer.DrawTimer),g);
调用
但出现如下错误 
g.FillEllipse(new SolidBrush(Color.Green), x1 - 5, y1 - 5, 10, 10);
参数无效 
高手帮解答