Easy SetParent question

I've done this before, but I can't remember how I got it working (and why it won't now). I want to set a form as a child of another form. I know I need to use the SetParent API, but it's like it doesn't see that line. My project is set up with frmMain and frmChannel. Here's the frmMain code:

Public Class frmMain
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "
' The standard stuff goes here, taken out to save space
#End Region

    Private Declare Function SetParent Lib "user32" Alias "SetParent" (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim objTest As New frmChannel
        SetParent(objTest.Handle.ToInt32, Me.Handle.ToInt32)
        objTest.Show()
    End Sub
End Class

According to http://www.allapi.net/ SetParent returns nonzero when it succeeds. When I used MsgBox to see what the output was, it was a really huge number (nonzero) but it didn't get set as a child. What am I doing wrong?

I'm using VB.NET 2003 in case you're wondering.