Нет такого сигнала / No such signal

#include <QString>
#include <QVector>
#include <vector>
#include <QObject>
#include <QTimer>
 
using namespace std;
 
class Engine : public QObject{
    Q_OBJECT
public:
    class Sensor{
    public:
        Sensor(const QString &name, int state, int priority = 0);
        ~Sensor();
        int getState();
        void setState(int);
    private:
        QString name;   // sensor name
 
        int state;      // state:
                        // 1 - true
                        // 0 - false
                        // any other number - defect sensor
 
        int priority;   // 1...5
    };
 
    Engine();
    Engine(const vector<Sensor> &list);
    ~Engine();
 
    void Start();
    void Stop();
 
    void AddSensor(const Sensor &item);
    void AddSensorList(const vector<Sensor> &list);
 
signals:
    void Alarm(Sensor item);
 
private slots:
    void Update();
 
private:
    vector<Sensor> *sensors;
    QTimer *timer;
    bool isBisy;
};

#include <engine.h>
 
 
 
Engine::Sensor::Sensor(const QString &name, int state, int priority)
    : name(name), state(state), priority(priority)
{
}
 
Engine::Sensor::~Sensor()
{
}
 
int Engine::Sensor::getState()
{
    return this->state;
}
 
void Engine::Sensor::setState(int state){
    this->state = state;
}
 
Engine::Engine()
    : isBisy(false)
{
    sensors = new vector<Sensor>();
 
    timer = new QTimer();
    timer->setInterval(500);    // 0.5 sec
    connect(timer, SIGNAL(timeout()), this, SLOT(Update()));
}
 
Engine::Engine(const vector<Engine::Sensor> &list)
    : isBisy(false)
{
    if(!list.empty())
        sensors = new vector<Sensor>(list);
    else
        sensors = new vector<Sensor>();
 
    timer = new QTimer();
    timer->setInterval(500);    // 0.5 sec
    connect(timer, SIGNAL(timeout()), this, SLOT(Update()));
}
 
Engine::~Engine()
{
    sensors->clear();
    delete sensors;
    delete timer;
}
 
void Engine::Start()
{
    if(!isBisy)
        timer->start();
    isBisy = true;
}
 
void Engine::Stop()
{
    if(isBisy)
        timer->stop();
    isBisy = false;
}
 
void Engine::AddSensor(const Engine::Sensor &item)
{
    sensors->push_back(item);
}
 
void Engine::Update()
{
    for(int i = 0; i < sensors->size(); ++i)
        if((*sensors)[i].getState() == 1)
            emit Alarm((*sensors)[i]);
}

#include <QObject>
#include <engine.h>
#include <iostream>
#include <conio.h>
 
using namespace std;
 
class App : public QObject{
Q_OBJECT
public:
    App();
 
public slots:
    void show(Engine::Sensor);
};

#include <app.h>
 
App::App()
{
    Engine engine;
    Engine::Sensor sen_1("window_1",0);
    engine.AddSensor(sen_1);
 
    sen_1.setState(1);
 
    connect(&engine, SIGNAL(Alarm(Engine::Sensor)), this, SLOT(show(Engine::Sensor)));
}
 
void App::show(Engine::Sensor sens)
{
    cout << sens.getState();
}