VB 弹出和关闭光驱

新建工程，添加一个窗体、三个按钮
按钮1：打开光驱。按钮2：关闭光驱。按钮3：退出
代码如下：
Option Explicit
Private Declare Function CDdoor Lib "winmm.dll" Alias "mciSendStringA" _
(ByVal lpstrCommand As String, ByVal lpstrReturnString As String, _
ByVal uReturnLength As Long, ByVal hwndCallback As Long) As Long

Dim state1 As Boolean

Private Sub Command1_Click()
'打开光驱
state1 = True
Call CDdoor("set CDAudio door open", 0, 0, 0)
End Sub

Private Sub Command2_Click()
'关闭光驱
state1 = False
Call CDdoor("set CDAudio door closed", 0, 0, 0)
End Sub

Private Sub Command3_Click()
End
End Sub