music player cannot load backend plugin

$ ./musicplayer
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
Phonon::createPath: Cannot connect Phonon::MediaObject(no objectName) to Phonon::AudioOutput(no objectName).
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded