WebParts and MOSS 2007

Okay...I have succesfully created and added a webpart programmically to MOSS 2007 (thank you Sahil Malik!!). The webpart displays a label and a button. However, when I click the button, the label is supposed to change from "Hello" to "Goodbye". The page reloads as though it went back to the server to find code for the click event, but the label does not change. Any help would be appreciated on this. If the solution deals with IPostBackEventHandler and its subsequent RaisePostBackEvent method, then can someone describe how to use this. Here's the code:

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Text
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Xml.Serialization
Imports System.Runtime.InteropServices
Imports System.Security
Imports System.Security.Permissions

<DefaultProperty("Text"), ToolboxData("<{0}:Test runat=server></{0}:WebCustomControl1>")> _
Public Class Test
Inherits WebPart
Dim lbl As New Label
Dim btn As New Button

<Bindable(True), Category("Appearance"), DefaultValue(""), Localizable(True)> Protected Overrides Sub CreateChildControls()
MyBase.CreateChildControls()
lbl.Text = "Hello"
btn.Text = "Click Me"
btn.ID = "Test"
AddHandler btn.Click, AddressOf btn_Click
Controls.Add(lbl)
Controls.Add(btn)
End Sub

Protected Sub btn_Click(ByVal s As Object, ByVal e As EventArgs)
lbl.Text = "Goodbye"
End Sub

Protected Overrides Sub RenderContents(ByVal output As HtmlTextWriter)
CreateChildControls()
lbl.RenderControl(output)
btn.RenderControl(output)
End Sub
End Class

Thanks!

Okay, found a partial solution.

As it turns out there are some things that are not needed with the code: The RenderControls procedure needs to be taken right out. Also, I have noticed through examples this code:

<AspNetHostingPermission(SecurityAction.Demand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermission(SecurityAction.InheritanceDemand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _

applied to the beginning of the webpart class. Is it needed? I am not sure, but since my webpart works now, I left it in. Btw, to use the above tags, be sure to import System.Security.Permissions

Now, the next thing is to work with the SelectedIndexChanged event. These seem to be causing errors.