Problem with QPushButton setDisabled SLOT

[code_err]

I was trying to find solution on forum but couldn't. The problem is i connected SIGNAL from QComboBox with QPushButton SLOT. I want it to be disabled after changing item from combo list but it doesn't work. When i connect this same SIGNAL with qApp quit() SLOT it works.

QObject::connect(&combo, SIGNAL(activated(int)), &button, SLOT(setDisabled()));

QObject::connect(&combo, SIGNAL(activated(int)), &button, SLOT(setDisabled()));

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Button inherits this SLOT from QWidget but i don't know why in the Qt Designer i cannot see this SLOT.

#include <QApplication>
#include <QtCore>
#include <QtGui>
 
int main(int argc, char **argv)
{
  QApplication app(argc, argv);
 
  QWidget window;
  QVBoxLayout *layout = new QVBoxLayout;
 
  QStringList list;
  list << "jeden" << "dwa" << "trzy" << "cztery" << QString::fromUtf8("pięć");
 
  QComboBox combo;
  combo.addItems(list);
 
  QPushButton button(QString::fromUtf8("Wyłącz się do cholery"));
 
  window.setLayout(layout);
 
  layout->addWidget(&combo);
  layout->addWidget(&button);
 
  QObject::connect(&combo, SIGNAL(activated(int)), &button, SLOT(setDisabled(bool)));
  QObject::connect(&button, SIGNAL(clicked()), qApp, SLOT(quit()));
 
  window.show();
  return app.exec();
}

#include <QApplication>
#include <QtCore>
#include <QtGui>

int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  
  QWidget window;
  QVBoxLayout *layout = new QVBoxLayout;
  
  QStringList list;
  list << "jeden" << "dwa" << "trzy" << "cztery" << QString::fromUtf8("pięć");
  
  QComboBox combo;
  combo.addItems(list);
  
  QPushButton button(QString::fromUtf8("Wyłącz się do cholery"));
  
  window.setLayout(layout);
  
  layout->addWidget(&combo);
  layout->addWidget(&button);
  
  QObject::connect(&combo, SIGNAL(activated(int)), &button, SLOT(setDisabled(bool)));
  QObject::connect(&button, SIGNAL(clicked()), qApp, SLOT(quit()));
  
  window.show();
  return app.exec();
}

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it is complete main.cpp

Ok, what is wrong with this code?