NetworkAnalystExtension オブジェクトの取得

Dim pMxDocument As IMxDocument
Set pMxDocument = ThisDocument

Dim pUID As New UID
Set pUID.Value = "esriNetworkAnalystUI.NetworkAnalystExtension"

Dim pNetworkAnalystExtension As INetworkAnalystExtension
Set pNetworkAnalystExtension = Application.FindExtensionByCLSID(pUID)
'FindExtensionByNameだと正常に取得できない