Android Question Why the MediaPlayer vuolume is always high?

Sub Activity_KeyPress(KeyCode As Int) As Boolean
Dim temp As Int
'Intercetta il volume e lo regola
  Select KeyCode
  Case KeyCodes.KEYCODE_VOLUME_DOWN
  temp = Main.Phone1.GetVolume(Main.Phone1.VOLUME_MUSIC)
  If temp > 0 Then temp = temp - 1 Else temp = 0
  Main.Phone1.SetVolume(Main.Phone1.VOLUME_MUSIC, temp, True)
  Return True
  Case KeyCodes.KEYCODE_VOLUME_UP
  temp = Main.Phone1.GetVolume(Main.Phone1.VOLUME_MUSIC)
  If temp < Main.Phone1.GetMaxVolume(Main.Phone1.VOLUME_MUSIC) Then
  temp = temp + 1
  Else
  temp = Main.Phone1.GetMaxVolume(Main.Phone1.VOLUME_MUSIC)
  End If  
  Main.Phone1.SetVolume(Main.Phone1.VOLUME_MUSIC, temp, True)
  Return True
   End Select
   End If

Return True
End Sub