Connect funktioniert nicht

[connector]

I have a mainwidget

class MainWindow : public QMainWindow
{
Q_OBJECT
[...]

public slots:
void SLOT_New(){exit(0);}  // To test for success

In the constructur of MainWindow Im trying to connect a signal with this slot:

QObject::connect(ptrTreeWidget, 
SIGNAL(itemSelectionChanged()), 
this,
SLOT(SLOT_New()));

But nothing happens, where could my mistake be?

// Bin deutsch, hab crossposting in nem QT Forum gemacht