QMediaPlayer

Hi I can not rewind media. It is a mp3 file. Forwarding with QMediaPlayer works fine. My code

playPos=player->position();
player->setPlaybackRate(-2);
player->setPosition(playPos);
player->play();

I also get this from program exit:

(MP3player:25462): GStreamer-CRITICAL **: 21:47:39.465: gst_segment_to_running_time_full: assertion 'stop != -1' failed

kind regards Tomaz