Display a custom Excel form as a taskbar button

I want to hide the Excel button on the taskbar and display a separate button for my custom form so that it looks like an application on its own. I know this has been covered a lot, but I am having problems with a specific problem: my code works fine when I find it, but not if I let it work fine. Here is the code that I placed in the module of the Userform1 class:

Option Explicit

Private 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

Private Declare Function DrawMenuBar _
    Lib "user32" ( _
        ByVal hWnd As Long) _
As Long

Private Declare Function FindWindowA _
    Lib "user32" ( _
        ByVal lpClassName As String, _
        ByVal lpWindowName As String) _
As Long

Private Const GWL_EXSTYLE = (-20)
Private Const GWL_STYLE As Long = (-16)
Private Const WS_EX_APPWINDOW = &H40000
Private Const WS_SYSMENU As Long = &H80000
Private Const WS_MINIMIZEBOX As Long = &H20000
Private Const WS_MAXIMIZEBOX As Long = &H10000

Private Sub UserForm_Activate()

Dim lFrmWndHdl As Long
Dim lStyle As Long

lFrmWndHdl = FindWindowA(vbNullString, Me.Caption)
lStyle = GetWindowLong(lFrmWndHdl, GWL_STYLE)
lStyle = lStyle Or WS_SYSMENU
lStyle = lStyle Or WS_MINIMIZEBOX
lStyle = lStyle Or WS_MAXIMIZEBOX
SetWindowLong lFrmWndHdl, GWL_STYLE, (lStyle)
lStyle = GetWindowLong(lFrmWndHdl, GWL_EXSTYLE)
lStyle = lStyle Or WS_EX_APPWINDOW
SetWindowLong lFrmWndHdl, GWL_EXSTYLE, lStyle
DrawMenuBar lFrmWndHdl
AppActivate ("Microsoft Excel")
ThisWorkbook.Application.Visible = False

End Sub

, AppActivate, , Excel . , , . , , , Excel.