Query String Encryption with HTTPModule

So I a encrypting my Query string using HTTPModule and everything is working well until I have a postback...So here is what my Code looks like and detailed steps which I found here: http://madskristensen.net/post/HttpModule-for-query-string-encryption.aspx
So I have added this to my web.config file:
< httpModules > < add type = " QueryStringModule " name = " QueryStringModule " /> </ httpModules > Added the Encryption code to my App_Config file:
Imports System Imports System.IO Imports System.Web Imports System.Text Imports System.Security.Cryptography Public Class QueryStringModule Implements IHttpModule Private Shared ReadOnly SALT As Byte() = Encoding.ASCII.GetBytes(ENCRYPTION_KEY.Length.ToString) Public Sub Dispose() Implements System.Web.IHttpModule.Dispose ...