F1 shortcut

Hi,

i want to connect in a modal dialog the F1 key to help button of a QDialogButtonBox. But if I press the F1 key the button is not activated. In the application this is the only object (button or action) connected with the F1 shortcut. Where is the error?

Code:

---

MyDialog:: MyDialog(QWidget *parent) : QDialog(parent),  ui(new Ui:: MyDialog)
{
   ui->setupUi(this);
   QPushButton *helpButton = ui->buttonBox->button(QDialogButtonBox::Help);
   helpButton->setShortcut(QKeySequence::HelpContents);
}

---