private void radioButton2_CheckedChanged(object sender, EventArgs e) { if (this.InvokeRequired) { ListOfReadyPlayer.Invoke((MethodInvoker)(() => ListOfReadyPlayer.Items.Clear())); } else { ListOfReadyPlayer.Items.Clear(); } client.SendQAForSTOPWait(); // ListOfReadyPlayer. ListOfReadyPlayer.Items.Clear(); }