vb托盘问题

'这是一个简单的托盘程序，点击命令按钮最小化到托盘，点击托盘图标返回正常状态
'创建一个按钮Command1
Const MAX_TOOLTIP As Integer = 64
Const NIF_ICON = &H2
Const NIF_MESSAGE = &H1
Const NIF_TIP = &H4
Const NIM_ADD = &H0
Const NIM_DELETE = &H2
Const WM_MOUSEMOVE = &H200
Const WM_LBUTTONDOWN = &H201
Const WM_LBUTTONUP = &H202
Const WM_LBUTTONDBLCLK = &H203
Const WM_RBUTTONDOWN = &H204
Const WM_RBUTTONUP = &H205
Const WM_RBUTTONDBLCLK = &H206
Const SW_RESTORE = 9
Const SW_HIDE = 0
Private Type NOTIFYICONDATA
cbSize As Long
hwnd As Long
uID As Long
uFlags As Long
uCallbackMessage As Long
hIcon As Long
szTip As String * MAX_TOOLTIP
End Type

Private Declare Function ShowWindow Lib "user32" (ByVal hwnd As Long, ByVal nCmdShow As Long) As Long
Private Declare Function Shell_NotifyIcon Lib "shell32.dll" Alias "Shell_NotifyIconA" (ByVal dwMessage As Long, lpData