Try this for volume:
[code]
Private Sub Slider1_Change()
MediaPlayer1.Volume = Slider1.Value
End Sub

Private Sub Slider1_Scroll()
MediaPlayer1.Volume = Slider1.Value
End Sub
[/code[
Set max of slider to 100 (If u using a vertical slider, set to -100, and use the ABS function - "MediaPlayer1.Volume = ABS(Slider1.Value)")

Set the min of slider to 0 (If u using a vertical slider, set to 0)