QObject::connect says "no such signal"

[MistaPain]

Hi,

I've been trying to use a QSpinBox in my project. I would like to use the signal "valueChanged(int i)" (as described in the documentation), but at runtime QObject::connect complains that there is no such signal ;-(

I thought that something with my code was wrong. But even the following small application is suffering the same problem:

#include <QtGui>
#include <QApplication>
 
int main(int argc, char **argv)
{
	QApplication app(argc, argv);
 
	QSpinBox sB;
 
	QObject::connect(
		&sB,  SIGNAL(valueChanged(int i)),
		&app, SLOT(quit())
	);
 
	sB.show();
	return app.exec();
}

#include <QtGui>
#include <QApplication>

int main(int argc, char **argv)
{
	QApplication app(argc, argv);

	QSpinBox sB;

	QObject::connect(
		&sB,  SIGNAL(valueChanged(int i)),
		&app, SLOT(quit())
	);

	sB.show();
	return app.exec();
}

To copy to clipboard, switch view to plain text mode 

I'm using QT 4.2.0 for Windows and MingW.

Can anyone spot the point where my mistake is? I'm really getting mad about this.