The media player doesnt play the next song but when i show a message box with the url of the song then the song plays

i have this code

 If AxWindowsMediaPlayer1.playState = WMPLib.WMPPlayState.wmppsStopped Then
            tempInt = gen.Next(0, listTracks.Items.Count - 1)
            currentTrack = tempInt
            If tempInt = playedBefore Then
                tempInt = gen.Next(0, listTracks.Items.Count - 1)
                currentTrack = tempInt
                AxWindowsMediaPlayer1.URL = listTracks.Items(tempInt)
              >  MessageBox.Show(AxWindowsMediaPlayer1.URL)
                AxWindowsMediaPlayer1.Ctlcontrols.play()
                playedBefore = currentTrack
            Else
                currentTrack = tempInt
                AxWindowsMediaPlayer1.URL = listTracks.Items(tempInt)
             >   MessageBox.Show(AxWindowsMediaPlayer1.URL)

                AxWindowsMediaPlayer1.Ctlcontrols.play()
                playedBefore = currentTrack
            End If

When the song ends the next songs doesn't play.But when i display the url of the song to a message Box then it plays(marked at the code)