need help finding the oldest directory that isn't empty using vb.net

can't seem to figure out how to get the oldest directory that isn't empty. i have tried the following code but end up getting the wrong directory

Private Function checkdiff()
        Try
            Dim folder As New DirectoryInfo("c:\program files")


            Dim oldest As DirectoryInfo = Nothing

            For Each dir As DirectoryInfo In folder.GetDirectories()
                If oldest Is Nothing Then
                    oldest = dir

                ElseIf dir.CreationTime < oldest.CreationTime Then

                    If dir.GetFiles.Length > 1 Then
                        oldest = dir
                    End If
                End If

            Next
            Dim difference As Long
            If oldest IsNot Nothing Then
                difference = DateDiff(DateInterval.Day, Date.Now, oldest.LastWriteTime)

                MsgBox("The difference in the date is: " & difference.ToString() & " Directory is : " & oldest.FullName)
            Else
                MsgBox("The directory does not exist")
            End If
        Catch ex As Exception
            MsgBox(ex.ToString())
        End Try

    End Function

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