c#多线程的问题

  我在处理一个按纽点击事件，一开始按纽显示　＂自动扫描＂，按下后线程启动，按纽标签变成＂扫描暂停＂，按下后线程暂停（t.sustend）, 标签变成＂继续扫描＂，线程继续 t.Resume(),.但是现在的问题是　按下扫描后，线程停不下来，事件仍然在继续，但是　t.threadstate 的状态却是　unstart，奇怪了，明明线程已经启动了，为什么还是unstart状态呢？？请高手指点，谢谢
private void autoscan_Click(object sender, EventArgs e)
        {
            huawangge_test = new huawangge(pictureBox6, true, 0, 0,20,20, 10,10, 0, 0, 100);
            t = new Thread(new ThreadStart(huawangge_test.drawgrid));
            //System.Threading.ThreadState state=t.ThreadState ;
           
            if (autoscan.Text == "自动扫描")
            { 
                t.Start();
               
                state = t.ThreadState;
                autoscan.Text = "暂停扫描";
             
   
            }
            else if (autoscan.Text == "暂停扫描")
            {
               
                if (t.ThreadState  == System.Threading.ThreadState.Running )
                {
                   
                    t.Suspend();
             
                    
                    
                } 
                autoscan.Text = "继续扫描";
            }
            else if (autoscan.Text == "继续扫描")
            {
               
                if (t.ThreadState ==System.Threading.ThreadState.Suspended)
                {
                    
                    t.Resume();
                   
                }
                autoscan.Text = "停止扫描";
            }
            
        }