'SerialDataReceivedEventHandler' is not working.

Please help me. 'SerialDataReceivedEventHandler' is not working.

Tell me. If you know other way.

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO.Ports;

namespace SerialPortCtrl {

 public class ComPort
 {
     SerialPort SP = new SerialPort();
     List<string> RevData = new List<string>();

     public ComPort()
     {
     }

     ~ComPort() 
     {
         SP.Close();            
     }

     private void SP_DataRecieved(Object sender, SerialDataReceivedEventArgs e)
     {
         RevData.Add(SP.ReadLine());
     }

     private void SP_ErrorRecieved(Object sender, SerialErrorReceivedEventArgs e)
     {
         RevData.Add("Error while receiving data. " + e.ToString()); 
     }
     
     public string GetData()
     {
         string RevStr = "";
         if ( RevData.Count == 0) return "";
         RevStr = RevData[0];
         RevData.RemoveAt(0);
         return RevStr;
     }

     public bool SendData(string Data)
     {
         if (SP.IsOpen)
         {
             SP.WriteLine(Data);
             return true;
         }
         else return false;
     }

     public bool Open(string PortName, int BaudRate = 9600, int DataBits = 8)
     {
         
         SP.PortName = PortName;
         SP.BaudRate = BaudRate;
         SP.DataBits = DataBits;
         SP.Parity = Parity.None;
         SP.StopBits = StopBits.One;
         SP.ReadTimeout = (int)500;
         SP.WriteTimeout = (int)500;
         SP.ReadBufferSize = 4;
         SP.WriteBufferSize = 4;

         SP.DtrEnable = true;
         SP.RtsEnable = true;

         SP.DataReceived += new SerialDataReceivedEventHandler(SP_DataRecieved);
         SP.ErrorReceived += new SerialErrorReceivedEventHandler(SP_ErrorRecieved);
         SP.Open();
         
         if (SP.IsOpen) return true; else return false; 
     }

     public void Close()
     {
         SP.Close();
     }
 }

}