SignalR - Problems with vb.net

I have a project on vb.net that previously did not have SignalR . I did the whole process of importing libraries with Nuget , I manually created the classes necessary for its operation, but I have not gotten it to work.

I simply try to send a notification to the clients from the server when a certain event occurs.

This would be the server part:

Imports System.Net
Imports System.Net.Sockets
Imports System.Threading
Imports Microsoft.AspNet.SignalR
Imports Owin

Public Class Startup
    Public Sub Configuration(app As IAppBuilder)
        ' Any connection or hub wire up and configuration should go here 
        app.MapSignalR()
    End Sub
End Class

Public Class MessageHub
    Inherits Hub
    Public Shared Contexto As IHubContext
    Public Sub EnviaMensaje(mensaje As String)
        Dim context = GlobalHost.ConnectionManager.GetHubContext("MessageHub")
        context.Clients.All.EnviaMensaje(mensaje)
    End Sub
End Class

Public Class Mensaje
    Public Usuario As String
    Public Mensaje As String
End Class

Partial Class Pisos_Pisos
    Inherits System.Web.UI.MasterPage
    Public Shared GroupEP As IPEndPoint = Nothing
    Private HiloDeEscucha As Threading.Thread
    Private IpLocal As IPAddress
    Public Shared Escuchador As UdpClient = Nothing
    Public Shared TablaEventos As New EventosDS.COM_EventosDataTable
    Public Shared AdaptadorEventos As New EventosDSTableAdapters.COM_EventosTableAdapter
    Private AdaptadorUsuario As UsuariosDSTableAdapters.Web_UsuariosTableAdapter
    Private TablaUsuario As UsuariosDS.Web_UsuariosDataTable
    Public Shared MessageHub As New MessageHub

Public Property Usuario() As String
    Get
        Return lblUsuario.Text
    End Get
    Set(ByVal value As String)
        lblUsuario.Text = value
    End Set
End Property

Public Property RutaFoto() As String
    Get
        Return Image1.ImageUrl
    End Get
    Set(ByVal value As String)
        Image1.ImageUrl = value
    End Set
End Property
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Dim AutentCookie As HttpCookie
    Dim Ticket As FormsAuthenticationTicket
    Dim strTicket As String
    Dim strRuta As String
    Dim strPerfil As String

    AutentCookie = Request.Cookies(FormsAuthentication.FormsCookieName)
    Ticket = FormsAuthentication.Decrypt(AutentCookie.Value)
    Usuario = Ticket.Name
    strTicket = Ticket.UserData.Trim
    strRuta = strTicket.Substring(0, strTicket.IndexOf(";")).Trim

    strPerfil = strTicket.Substring(strRuta.Length + 1).Trim
    If strPerfil = "ADMINISTRADOR" Then
        LBSubGobernantas.Visible = True
        LBDiariosSubG.Visible = True
    Else
        LBSubGobernantas.Visible = False
        LBDiariosSubG.Visible = False
    End If

    RutaFoto = "~/Images/Personal/" & strRuta
    lblAhora.Text = "Inicio de conexión: " & Now.ToString

    IniciarEscucha()
End Sub

Protected Sub LBCerrarSesion_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles LBCerrarSesion.Click
    FormsAuthentication.SignOut()
    Response.Redirect("~\Default.aspx", True)
End Sub

Public Sub IniciarEscucha()

    If GroupEP Is Nothing Then
        GroupEP = New IPEndPoint(IPAddress.Any, 19500)
    End If
    HiloDeEscucha = New Thread(AddressOf Escuchar)

    HiloDeEscucha.Start()
End Sub
Private Sub Escuchar()
    Dim mensaje As String = ""
    Try
        Escuchador = New UdpClient(19500)
    Catch excSock As System.Net.Sockets.SocketException
        If Escuchador Is Nothing Then
            Exit Sub
        End If
    End Try

    While True

        Try
            Dim Bytes As Byte() = Escuchador.Receive(GroupEP)
            mensaje = System.Text.Encoding.Default.GetString(Bytes)
        Catch e1 As ThreadAbortException
            Exit While
        Catch e2 As Exception
        End Try

        If mensaje.Contains("RACK") And Not mensaje.Contains(My.Computer.Name) Then
            If mensaje.Contains("|") Then
                MessageHub.EnviaMensaje(mensaje.Substring(mensaje.IndexOf("|") + 1))
            End If
        End If

    End While
End Sub

End Class

The client part (javascript), would be the following:

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<script src="..." ></script>
<script src="..."></script>
<script src="..."></script>


<asp:ContentPlaceHolder ID="head" runat="server">
</asp:ContentPlaceHolder>
<link href=".." rel="stylesheet" type="text/css" />

<style type="text/css">
    .style1
    {
        width: 730px;
        text-align: left;
    }
    .style2
    {
        height: 49px;
    }
    .style3
    {
        width: 730px;
        text-align: left;
        height: 49px;
    }
</style>

<script type="text/javascript">
    $(document).ready(function () {

        var proxy = $.connection.MessageHub;

        proxy.client.EnviaMensaje = function (mensaje) {
            document.getElementById('player').play();
            $("#lblNotificacion").text(mensaje);
        }

        $.connection.hub.start().done(function () { $("#lblNotificacion").text("Conexión establecida!") });

        }
    );
</script>

(...)

If I execute the project, I have the following error on the client side:

jQuery.Deferred exception: Cannot read property 'client' of undefined TypeError: Cannot read property 'client' of undefined
    at HTMLDocument.<anonymous> (...)
    at mightThrow (...)
    at process () undefined

I've been stuck for two weeks and searching the Internet. It is very likely that it is silly, but I can not find the solution. Could someone help me?