vba - ツリービューを使用して MS Access '10 の自己参照テーブルに基づく階層を作成する

Question

このマイクロソフトの投稿の指示に従おうとしていました: http://support.microsoft.com/default.aspx?scid=kb;en-us;209891

例のように、自己参照テーブルに基づいて組織階層図を作成します。変数が未定義であり、VBA が「Optional varReportToID As Variant」という行を指しているというエラーが表示され続けますが、このパラメーターには何も指定しないように指示されています。コードを実行するためにできることはありますか? コードは変更しませんでした。テーブルの名前を、リストされている変数に一致するように変更しました。私は MS Access 2010 で作業していますが、例は古いバージョンの MS のものです。

ありがとう！

Option Explicit

'=================Load Event for the Form=======================
'Initiates the routine to fill the TreeView control
'============================================================

Public Sub Form_Load()
    Const strTableQueryName = "Employees"
    Dim db As DAO.Database, rst As DAO.Recordset
    Set db = CurrentDb
    Set rst = db.OpenRecordset(strTableQueryName, dbOpenDynaset, dbReadOnly)
    AddBranch rst:=rst, strPointerField:="ReportsTo", strIDField:="EmployeeID",      strTextField:="LastName"
End Sub

'================= AddBranch Sub Procedure ======================
'      Recursive Procedure to add branches to TreeView Control
'Requires:
'   ActiveX Control:  TreeView Control
'              Name:  xTree
'Parameters:
'               rst:  Self-referencing Recordset containing the data
'   strPointerField:  Name of field pointing to parent's primary key
'        strIDField:  Name of parent's primary key field
'      strTextField:  Name of field containing text to be displayed
'=============================================================
Sub AddBranch(rst As Recordset, strPointerField As String, _
          strIDField As String, strTextField As String, _
          Optional varReportToID As Variant)
    On Error GoTo errAddBranch
    Dim nodCurrent As Node, objTree As TreeView
    Dim strCriteria As String, strText As String, strKey As String
    Dim nodParent As Node, bk As String
    Set objTree = Me!xTree.Object
    If IsMissing(varReportToID) Then  ' Root Branch.
        strCriteria = strPointerField & " Is Null"
    Else  ' Search for records pointing to parent.
        strCriteria = BuildCriteria(strPointerField, _
            rst.Fields(strPointerField).Type, "=" & varReportToID)
        Set nodParent = objTree.Nodes("a" & varReportToID)
    End If

    ' Find the first emp to report to the boss node.
    rst.FindFirst strCriteria
    Do Until rst.NoMatch
        ' Create a string with LastName.
        strText = rst(strTextField)
        strKey = "a" & rst(strIDField)
        If Not IsMissing(varReportToID) Then  'add new node to the parent
            Set nodCurrent = objTree.Nodes.Add(nodParent, tvwChild, strKey, strText)
        Else    ' Add new node to the root.
            Set nodCurrent = objTree.Nodes.Add(, , strKey, strText)
        End If
        ' Save your place in the recordset so we can pass by ref for speed.
        bk = rst.Bookmark
        ' Add employees who report to this node.
        AddBranch rst, strPointerField, strIDField, strTextField, rst(strIDField)
        rst.Bookmark = bk     ' Return to last place and continue search.
        rst.FindNext strCriteria   ' Find next employee.
    Loop

'--------------------------Error Trapping --------------------------
    errAddBranch:
        MsgBox "Can't add child:  " & Err.Description, vbCritical, "AddBranch Error:"
        Resume exitAddBranch
End Sub