QShortcut doesn't work

I cannot get the shortcut to work. Here is the code:

class Interface : public QObject 
{
    Q_OBJECT

    private:

    QMainWindow myWindow;
    QWidget mainWidget;
    QShortcut shortcut;

    public:

    Interface();
    ~Interface();
    void show(void);

    public slots:

    void haha(void);
};

Interface::Interface() : 
    QObject(),
    shortcut(QKeySequence(Qt::Key_Enter), &mainWidget)
{
    myWindow.setFixedSize(1200, 600);
    myWindow.setCentralWidget(&mainWidget);
    QObject::connect(&shortcut, SIGNAL(activated()), this, SLOT(haha()));
}

void Interface::show(void)
{
    myWindow.show();
}

void Interface::haha(void)
{
    std::cout << "foo" << std::endl;
}

      

        
        
        
      

    

My main function:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QTextCodec::setCodecForCStrings(QTextCodec::codecForName("UTF-8"));
    QTextCodec::setCodecForTr(QTextCodec::codecForName("UTF-8"));

    Interface myInterface;
    myInterface.Show();
    return app.exec();
}

      

        
        
        
      

    

It compiles without any warnings / errors, but when I execute it, pressing "Enter" does not print "foo". I've already browsed the internet, but I didn't find something close enough. Sorry if I missed something important.