Audio CD playing issue usinf Phonon

Starting from the demos/QMediaPlayer from Qt-4.7.0-beta2, method "void MediaPlayer::openFile()", I read the tracks from an audio CD, add them to queue and start playback.
The problem here is that when I try to go to next track, it won't go. Also, after playing something from an audio CD, it won't play anything else: audio or video (no errors displayed).
If I compile it with Qt-4.6, everything goes well.

Here is my audioCD playing:

void MediaPlayer::playAudioCD()
{
const bool hasPausedForDialog = playPauseForDialog();
QStringList fileNames;
int num;
char* buff = (char*)malloc(10);

this->playingType = PLAY_AUDIOCD;

num = get_tracks_num("/dev/sr0");
if(!num)
return;

for(int i=0;i<num;i++)

{ sprintf(buff, "cdda://%d", i+1); fileNames.append(buff); }

if (hasPausedForDialog)
m_MediaObject.play();

m_MediaObject.clearQueue();
if (fileNames.size() > 0)

{ QString fileName = fileNames[0]; setFile(fileName); for (int i=1; i<fileNames.size(); i++) m_MediaObject.enqueue(Phonon::MediaSource(fileNames[i])); }

forwardButton->setEnabled(m_MediaObject.queue().size() > 0);

free(buff);
}