ShowWithoutActivation isn't working

[DougRenwick]

I'm an trying to prevent my application from stealing the focus from the application that launched it. Overriding the ShowWithoutActivation property returns a value of true but does not prevent the application from activating.
Why is this not working?

Public Class Form1
Sub New()
InitializeComponent()
End Sub
Protected Overrides ReadOnly Property ShowWithoutActivation() As Boolean
Get
ShowWithoutActivation = True
Return ShowWithoutActivation
End Get
End Property

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim n As Boolean
n = Me.ShowWithoutActivation
End Sub
End Class

Similarly using the ShowWindow( ) API function works until it reaches the end of Form1_Load.

Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Win32.ShowWindow(Me.Handle, Win32.SW_SHOWNOACTIVATE)
For i As Int64 = 1 To 900000000
Next
End Sub
End Class
Public Class Win32
Declare Function ShowWindow Lib "user32" ( _
ByVal hWnd As Int32, ByVal nCmdShow As Int32) As Int32
Public Const SW_HIDE = 0
Public Const SW_SHOWNOACTIVATE = 4
End Class

I don't understand why the form continues to activate. I have been working on this problem for a week now and I am at the end of my rope. Any help would be greatly appreciated.

Doug