Why cant change textbox text in client function SignalR - asp.net

Question

I just start testing signalr and I am trying to add text to a rich text box after I got a response from my HUB class , but it doesn't work (no text is shown in my richtextbox) I don't know why...(the code run with no errors)
//server
public class ConnectByHub : Hub
{
public void testFunc(mas) {
string ans = mas + " got it";
Clients.All.testFunc(ans);
} }
//Client
private async void connectToServer()
{
Connection = new HubConnection(LocalClient);
HubProxy = Connection.CreateHubProxy("ConnectByHub");
try
{
await Connection.Start();
}
catch (Exception ex)
{
return;
}
string msg = "Hello friend!";
HubProxy.Invoke("testFunc", (msg)).Wait();
// Option one - doesn't work
HubProxy.On<string>("testFunc", (param) => Invoke((Action)(() => { MsgTxtBox.Text = "something happened"; })));
//Option two - doesn't work
HubProxy.On<string>("testFunc", (param) => this.Invoke((Action)(() => { MsgTxtBox.AppendText("Something happend " + Environment.NewLine); })));
}

Answer 1

I think part of the problem is trying to send a message from the same Async method (connectToServer) in which your listener is running.
I mostly used the same code from the question but moved a couple things around:
Moved HubProxy.Invoke() out of the Async method and called it from a button_click event
Called string.format() on the parameter
SERVER:
public class ConnectByHub : Hub
{
public void Send(string message)
{
Clients.All.testFunc(message);
}
}
CLIENT:
// Added button event
private void button1_Click(object sender, EventArgs e)
{
string msg = "Hello friend!";
HubProxy.Invoke("Send", msg).Wait();
}
private async void ConnectToServerAsync()
{
Connection = new HubConnection(LocalClient);
HubProxy = Connection.CreateHubProxy("ConnectByHub");
// Put the parmater in string.format()
HubProxy.On<string>("testFunc", (param) => this.Invoke((Action)(() => MsgTxtBox.AppendText(string.Format("{0}", param)))));
try
{
await Connection.Start();
}
catch (Exception ex)
{
richTextBox1.AppendText(string.Format("Unable to Connect to server ({0})", ServerURI));
return;
}
}