[RESOLVED] Programming Challenge (not homework) Editing many files quickly

[stateofidleness]

here's what I came up with while waiting to see if someone else could knock something out:

Imports System.IO
 
Public Class Form1
 
    Dim srcFilename As String = ""
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
    End Sub
 
    Private Sub replaceButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles replaceButton.Click
        Dim path As String = "MyFilePath"
        Dim dDir As New DirectoryInfo(path)
        Dim fFileSystemInfo As FileSystemInfo
        For Each fFileSystemInfo In dDir.GetFileSystemInfos()
            Dim fs As New FileStream(fFileSystemInfo.FullName, FileMode.Open, FileAccess.ReadWrite)
            Dim ioFile As New StreamReader(fs)
            Dim myText As String = ioFile.ReadLine()
            If myText = "stringImsearchingfor"
                myText.Replace(myText, "replacementtext")
                filesListbox.Items.Add(fFileSystemInfo.Name)
            Else
                Me.notEditedTextbox.Text &= Environment.NewLine & fFileSystemInfo.Name
            End If
            ioFile.Close() 'Close file
        Next
    End Sub
End Class

the condition is being met correctly and the files (edited and nonedited) get added to the correct control (listbox if edited, textbox if not edited) but the files themselves are not being updated. am i missing something?