一个OPC DA VB程序（网上download的），编译出现“User-defined type not defined” 错误（注意：我已经添加了reference OPC Automation 2.0 ）其代码如下： Public OpcServer As IOPCServerDisp ‘OPC Server Object Public OpcItemMgt As IOPCItemMgtDisp ’OPC Group Object Public OpcItem As IOPCItemDisp ‘OPC Item Object 发现它与通常的代码不同，通常的DA client代码是这样的： Dim WithEvents Myserver As OPCServer Dim WithEvents Mygroup As OPCGroup Dim WithEvents Mygroups As OPCGroups Dim Myitem As OPCItem Dim Myitems As OPCItems Dim MyBrowser As OPCBrowser 哪位大侠能告诉我这是什么原因？是不是DA 1.0的接口？