metadata in Mediaplayer are undefined

[Judicael Bayoli]

Hi every body, I'm working in a app to play mp3 files, so I wrote this code

MediaPlayer {
     id: player
     source: "qrc:/music/lecrae-fear.mp3"
}

Text {
     id: musicTitle
     text: player.metaData.title
}

This is just a part of my code, the problem is in the application out put I get message that say : Unable to assign a [undefined] to a QString. I don't know how I could fix it. Thanks for your helps