private void button2_Click(object sender, EventArgs e) { try { phidget.CloseRFID(); phidget.RFID.Tag -= new RFIDTagEventHandler(AssignARFID); // phidget.RFID.Tag += new RFIDTagEventHandler(RFIDTagNr); if (RFIDTagNr == null) { MessageBox.Show("Please scan the rfid chip"); } } catch (Exception) { MessageBox.Show("There was an error closing the rfid reader."); } this.Close(); }