utiliser une classe pour gerer les signaux

Bonjour,
Intro: j'ai besoin de synchroniser les differents elements (deux Slider, SpinBox et QLCDNumber) en les mettant a la meme valeur en passant par une classe qui va recevoir et generer les signaux (SigMan)..

Pb: le compilateur renvoie le message suivant:
release\q3.o(.text+0x5d):q3.cpp: underfined reference to 'vtable for SigMan'
release\q3.o(.text+0x12d):q3.cpp: underfined reference to 'vtable for SigMan'
release\q3.o(.text+0x1b3):q3.cpp: underfined reference to 'SigMan::valueChanged(int)'

Sources:

Code:

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class MyWidget : public QWidget
 {
 public:
     MyWidget(QWidget *parent = 0);
 };
 
class SigMan: public QObject
{
	Q_OBJECT
 
		private:
			int value;
		public:
			SigMan(int val=0);
		signals:
			void valueChanged(int);
		public slots:
			void setValue(int);
};
 
SigMan::SigMan(int n):
	QObject()
{
	value=n;
}
void SigMan::setValue(int n)
{
	value=n;
	emit valueChanged(value);
}			
 
 MyWidget::MyWidget(QWidget *parent)
     : QWidget(parent)
 {
 
 
     QSlider *lcd = new QSlider(Qt::Horizontal);
     lcd->setRange(0, 99);
     lcd->setValue(20);
 
     QSlider *slider = new QSlider(Qt::Horizontal);
     slider->setRange(0, 99);
     slider->setValue(0);
 
     QSpinBox *qsb= new QSpinBox();
     qsb->setRange(0,99);
 
	QLCDNumber *nb=new QLCDNumber;
 
	SigMan *s=new SigMan;
 
    connect(slider,SIGNAL(valueChanged(int)),s,SLOT(setValue(int)));
    connect(lcd,SIGNAL(valueChanged(int)),s,SLOT(setValue(int)));
	connect(qsb,SIGNAL(valueChanged(int)),s,SLOT(setValue(int)));
	connect(s,SIGNAL(valueChanged(int)),slider,SLOT(setValue(int)));
	connect(s,SIGNAL(valueChanged(int)),lcd,SLOT(setValue(int)));
	connect(s,SIGNAL(valueChanged(int)),qsb,SLOT(setValue(int)));
	connect(s,SIGNAL(valueChanged(int)),nb,SLOT(display(int)));
 
     QVBoxLayout *layout = new QVBoxLayout;
     layout->addWidget(lcd);
     layout->addWidget(slider);
     layout->addWidget(qsb);
     layout->addWidget(nb);
     setLayout(layout);
 }
 
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     MyWidget widget;
     widget.show();
     return app.exec();
 }

Merci..