Trouble with export text in visual basic to .txt file

Hi:

I've produced the following code:

Public Class background

    Dim stRep As String
    Dim strReport As String
    Dim oFSO As Object
    Dim objReport As Object

    Private Sub MakeFile1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MakeFile1.Click
        strReport = "report.txt"

        stRep = InputBox(TextBox1.Text)
        SetAttr(oFSO = CreateObject("Scripting.FileSystemObject"))
        SetAttr(objReport = oFSO.CreateTextFile(strReport, True))

        If oFSO.FolderExists(stRep) Then
            For Each oF1 In oFSO.GetFolder(stRep).Files
                objReport.WriteLine(oF1.Name)
            Next
        End If

        objReport.Close()

    End Sub

    Private Sub SetAttr(ByVal p1 As Object)
        Throw New NotImplementedException
    End Sub

End Class
=================================
The goal is to create a .txt file and append it if it already exists.  I'm working in VB 2010.  However, the bolded line is giving me trouble.  I've received the following message at runtime....

Operator '=' is not defined for 'Nothing' and type 'FileSystemObject'.

Any ideas on how to address this?  I will keep doing research, but would appreciate feedback!

Robert