ASP MVC SignalR null

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Microsoft.AspNet.SignalR;
using Microsoft.AspNet.Identity;
using System.Web.Security;
using Communicator.Models;
using System.Threading.Tasks;
using System.Diagnostics;
using System.Security.Cryptography;

namespace Communicator.Hubs
{
    public class ChatHub : Hub
    {
        private DefaultConnection Datebase = new DefaultConnection();
        static private List<string> ActiveGroups = new List<string>();

        private string GetCallerGroupName()
        {
            return Context.User.Identity.GetUserId<string>();
        }

        private bool CheckIfUserIsAvaibleNow(string UserId)
        {
            string FoundUser = ActiveGroups.Find(x => x == UserId);
            return FoundUser != null ? true : false ;
        }

        public override async Task OnConnected()
        {
#if DEBUG
            var id = Context.ConnectionId;
            Debug.WriteLine("OnConnected: " + id.ToString());
#endif

            await Groups.Add(Context.ConnectionId, GetCallerGroupName());
            ActiveGroups.Add(GetCallerGroupName());

            await base.OnConnected();
        }


        public override async Task OnDisconnected(bool StopCalled)
        {

#if DEBUG
            var id = Context.ConnectionId;
            Debug.WriteLine("OnConnected: " + id.ToString());
#endif


            await Groups.Remove(Context.ConnectionId, GetCallerGroupName());
            ActiveGroups.Remove(GetCallerGroupName());

            await base.OnDisconnected(StopCalled);
        }

        public override Task OnReconnected()
        {
#if DEBUG
            var id = Context.ConnectionId;
            Debug.WriteLine("OnReconnected: " + id.ToString());
#endif

            return base.OnReconnected();
        }

        public void GetToken()
        {
            byte[] Time = BitConverter.GetBytes(DateTime.UtcNow.ToBinary());
            byte[] Key = Guid.NewGuid().ToByteArray();
            string Token = Convert.ToBase64String(Time.Concat(Key).ToArray());
            Clients.Caller.ServerMessage("Your token: " + Token, DateTime.Now);
            Clients.Caller.GetToken(Token);
        }

        public void GetHistory()
        {
            string UserIdFrom = Context.User.Identity.GetUserId<string>();

            var messages = Datebase.Messages.ToList();

        }


        public void Send(string Message,
                         string UserIdTo,
                         string Token)
        {
            string UserIdFrom = Context.User.Identity.GetUserId<string>();
            bool IsUserToActive = CheckIfUserIsAvaibleNow(UserIdTo);
            MessageFlagType Flag = MessageFlagType.MESSAGE_WAITING_FOR_DELIVER;

            if (IsUserToActive)
            {
                Flag = MessageFlagType.MESSAGE_SENDED;
            }

            try
            {

                Message SendedMessage = new Message(Message,
                                                    UserIdTo,
                                                    UserIdFrom,
                                                    DateTime.Now,
                                                    Context.Request.Environment["server.RemoteIpAddress"].ToString(),
                                                    Token,
                                                    Flag);
#if DEBUG
                Debug.WriteLine(SendedMessage.ToString());
#endif

                Datebase.Messages.Add(SendedMessage);
                Datebase.SaveChangesAsync();


                Clients.Caller.message(UserIdFrom, Message, DateTime.Now);

                if (IsUserToActive)
                {
                    Clients.Group(UserIdTo).message(UserIdFrom, Message, DateTime.Now);
                }

            }
            catch (Exception exception)
            {
                Clients.Group(GetCallerGroupName()).ServerMessage(exception.Message,
                                                                  DateTime.Now);
            }
            
        }


    }
}