使用VBA从Outlook AddressBook中的项目获取别名

我下面的代码在Debug.Print（oExuser.Alias）中显示以下错误，原因是什么？

子测试（）

Dim AliasName, FullName As String
Dim outlookApp As Outlook.Application
Dim myNameSpace As Outlook.nameSpace
Dim myAddrList As AddressList
Dim myAddrEntries As AddressEntries
Dim myAddrEntry As Outlook.AddressEntry
Dim myAlias As Object
Dim oExUser As Outlook.ExchangeUser

Set outlookApp = New Outlook.Application
Set myNameSpace = outlookApp.GetNamespace("MAPI")
Set myAddrList = myNameSpace.GetGlobalAddressList()


Set myAddrEntries = myAddrList.AddressEntries
Set myAddrEntry = myAddrEntries.Item(1)

Set oExUser = myAddrEntry.GetExchangeUser

Debug.Print (oExUser.Alias)

End Sub