Replace audio file in powerpoint

[papuapu]

Need a little help.
I have two slides with animations & in slide(2) have an audio file.I want to replace this audio file. When I use below code I replaced the audio file successfully but lost slide(2) animation.I can not configure it out.Any other solution will be appreciated.

Option Explicit

Sub ReplaceMediaFormat()
    Dim sld As Slide
    Dim newShp As Shape
    Dim shp As Shape
    Dim mf As MediaFormat
    Dim path As String
    Dim fDialog As FileDialog
    Dim filepath As String
    MsgBox "Please select/browse audio-background file from your computer! "
    Set fDialog = Application.FileDialog(msoFileDialogFilePicker)
    ' Optional: FileDialog properties
    fDialog.AllowMultiSelect = False
    fDialog.Title = "Select a Audio file"
    fDialog.InitialFileName = "C:"
    ' Optional: Add filters
    fDialog.Filters.Clear
    fDialog.Filters.Add "Audio files", "*.mp3"
    fDialog.Filters.Add "All files", "*.*"
    ' Show the dialog. -1 means success!
    If fDialog.Show = -1 Then
        filepath = fDialog.SelectedItems(1)
    Else
    End If
    Set sld = ActivePresentation.Slides(2)
    Set shp = sld.Shapes("bg_music")
    Set mf = shp.MediaFormat
    Set newShp = sld.Shapes.AddMediaObject2(filepath)
    With newShp
         .Top = shp.Top
         .Left = shp.Left
         .Width = shp.Width
         .Height = shp.Height
    End With
    With newShp.MediaFormat
         .StartPoint = mf.StartPoint
         .EndPoint = mf.EndPoint
         .FadeInDuration = mf.FadeInDuration
         .FadeOutDuration = mf.FadeOutDuration
         .Muted = mf.Muted
         .Volume = mf.Volume
     End With
    shp.Delete
    Dim eff As Effect
    Set eff = sld.TimeLine.MainSequence.AddEffect(newShp, msoAnimEffectMediaPlay, trigger:=msoAnimTriggerWithPrevious)
    With newShp.AnimationSettings.PlaySettings
         .LoopUntilStopped = msoTrue
         .PauseAnimation = msoFalse
         .PlayOnEntry = msoTrue
         .RewindMovie = msoFalse
         .StopAfterSlides = 999
         .HideWhileNotPlaying = msoTrue
    End With
    newShp.Name = "bg_music"
End Sub