vb 2008 接收消息的问题。

我用vb6作了一个接收消息的程序，没问题。
把该程序转移到vs2008的时候就出现了问题：
'UPGRADE_WARNING: Add a delegate for AddressOf WindowProc

运行也出现错误， 通过查询很多资料后，勉强可以，可是有warning。
期待高人。
vb6的代码大概如下：
Private Declare Function CallWindowProc Lib "user32" Alias _
"CallWindowProcA" (ByVal lpPrevWndFunc As Long, _
ByVal hwnd As Long, ByVal Msg As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long

Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _
(ByVal hwnd As Long, ByVal nIndex As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias _
"SetWindowLongA" (ByVal hwnd As Long, _
ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Public Function Hook(ByVal hwnd As Long) As Long
Dim pOld As Long

pOld = SetWindowLong(hwnd, GWL_WNDPROC,AddressOf WindowProc)

SetWindowLong hwnd, GWL_USERDATA, pOld
Hook = pOld
End Function

Public Sub Unhook(ByVal hwnd As Long, ByVal lpWndProc As Long)
Dim temp As Long
temp = SetWindowLong(hwnd, GWL_WNDPROC, lpWndProc)
End Sub

Function WindowProc(ByVal hw As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
If uMsg = WM_USER + 1 Then
MsgBox "msg received" & wParam 'wParam
End If
Dim lpPrevWndProc As Long
lpPrevWndProc = GetWindowLong(hw, GWL_USERDATA)
WindowProc = CallWindowProc(lpPrevWndProc, hw, uMsg, wParam, lParam)
End Function