SignalR overwriting OnConnected(), OnDisconnected()

I'm trying to overwrite OnConnected(), OnDisconnected() methods but I get: OnConnected()': no suitable method found to override

Is implementing IDisconnect, IConnect interfaces and doing my processing within Connect() and Disconnect() the same as OnConnected(), OnDisconnected()?

what gives?

   public static class UserHandler
    {
        public static HashSet<string> ConnectedIds = new HashSet<string>();
    }

    public class MyHub : Hub
    {
        public override Task OnConnected()
        {
            UserHandler.ConnectedIds.Add(Context.ConnectionId);
            return base.OnConnected();
        }

        public override Task OnDisconnected()
        {
            UserHandler.ConnectedIds.Remove(Context.ConnectionId);
            return base.OnDisconnected();
        }
    }