Sending text from ChatForm.cs to chathandler.cs to server does not work

        private void Sendpacket_Click(object sender, EventArgs e)
        {
            try
            {
                if (txtMessage.Text.Trim() != "")
                {
                    ChatHandler.ClientToServer(txtMessage.Text);
                    AddMessage("Me", txtMessage.Text.Trim());
                    txtMessage.Text = "";
                    txtMessage.Focus();
                }
            }

    public class ChatHandler : IMessageProcessor
    {


        ISender sender;

        public bool CanExecute(IMessage message) => message is DoChat || message is DoKillChatForm || message is DoStartChatForm;

        public bool CanExecuteFrom(ISender sender) => true;

        public void Execute(ISender sender, IMessage message)
        {
            switch (message)
            {
                case DoKillChatForm Msg:
                    closechat();
                    break;
                case DoStartChatForm Msg:
                    startchat();
                    break;
                case DoChat Msg:
                    OnDataReceived(Msg.PacketDms);
                    break;
            }
        }
        public void ClientToServer(string message)
        {
            try
            {
                sender.Send(new GetChat { Message = message.ToString() });
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error sending message: {ex.Message}");
            }
        }