What to do to reject a replace txt file request, and offer them to create new txt file instead?

Using this codes, I don't know what's wrong, I still can't solve my problem

Please check and correct me. What's wrong?

What I want is when they click the savefile button, savefiledialog will show to save the data to a file. If they try to replace an existing file, Msgbox will show to reject their replace request. So they have to create new file.

With this code, this is what's happening.

1st click, you can create or replace without getting reject messagebox.

2nd click, you will receive rejection either you create or replace.

3rd click is like the 1st click

4th click is like the 2nd click

And so on.

Private lastSaveFileName As String = String.Empty
Private Sub SaveFile_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SaveFile.Click
    lastSaveFileName = GetSaveFileName2(lastSaveFileName)
    If Not String.IsNullOrEmpty(lastSaveFileName) Then
        File.AppendAllText(lastSaveFileName, txtdisplay1.Text)
    End If


End Sub

Private Function GetSaveFileName2(ByVal suggestedName As String) As String
   
        Using sfd3 As New SaveFileDialog()
            sfd3.Filter = "Text Files (*.txt) |*.txt"
            sfd3.FileName = suggestedName
        sfd3.OverwritePrompt = False


        If sfd3.ShowDialog() = DialogResult.OK Then
            If Not File.Exists(lastSaveFileName) Then
                MessageBox.Show(
            Me, "Your activity is not saved! This file have records from your last session, you cannot overwrite this file. Please create new file to save new records.",
            "Save error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation
        )
            Else
                Return sfd3.FileName
            End If

            
        Else


        End If

            Return String.Empty
        End Using


End Function

This is related to my first post, How to WriteAllText but restrict to overwrite the existing file?

Like this,

Private Function GetSaveFileName2(suggestedName As String) As String
    Dim rv As String = String.Empty 'String.Empty is do not save
    Dim sfd3 As New SaveFileDialog()
    sfd3.Filter = "Text Files (*.txt) |*.txt"
    sfd3.FileName = suggestedName
    sfd3.OverwritePrompt = False
    Dim dr As DialogResult
    Do
        dr = sfd3.ShowDialog
        If dr = DialogResult.OK Then
            If IO.File.Exists(sfd3.FileName) Then
                MessageBox.Show("Not saved! .... Please create new file to save new records or Cancel to Exit.",
                                    "Save error",
                                    MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
            Else
                rv = sfd3.FileName
            End If
        End If
    Loop While dr = Windows.Forms.DialogResult.OK AndAlso rv = String.Empty
    Return rv
End Function