почему нельзя кастить QObject* к QDBusInterface*?

с помощью qobject_cast:КодC++ (Qt)QDBusInterface *i = qobject_cast(sender());Цитировать/usr/include/qt4/QtDBus/qdbusabstractinterface.h: In member function void QDBusAbstractInterface::qt_check_for_QOB JECT_macro(const T&) const [with T = QDBusInterface]:/usr/include/qt4/QtCore/qobject.h:441: instantiated from T qobject_cast(QObject*) [with T = QDBusInterface*]dbus.cpp:151: instantiated from here/usr/include/qt4/QtDBus/qdbusabstractinterface.h:66: error: void value not ignored as it ought to be