Sending a variable Byref to a class

[Graff]

I want to be able to send a Richtextbox to one of my classes byref so that updates to the class rtb will update the actual rtb

Right now I have

Public Class InfLog
 
    Private Buffer1, Buffer2 As String
    Private Interval As Integer = 500
    Private rtxtbox As RichTextBox
 
    Public Sub New(ByVal Buffer1 As String, ByVal Buffer2 As String, ByRef rtb As RichTextBox)
        Me.Buffer1 = Buffer1
        Me.Buffer2 = Buffer2
        Me.rtxtbox = rtb
    End Sub

However when I make changes to rtxtBox nothing happens. Can someone please point me in the right direction?