在 C# 中连接到 ActiveDirectory 失败

我尝试在 C# 中连接到 AD

如果我连接到根目录，它会成功而不会引发错误。

        try {
            DirectoryEntry de = new DirectoryEntry("LDAP://COMPANYDOMAIN.COM", "username", "password");
            object nativeObject = de.NativeObject;
        } catch(DirectoryServicesCOMException) { }

如果我使用如下所示的另一种方式连接，它会抛出the specified domain either does not exist or could not be contacted.

        try {
            DirectoryEntry de = new DirectoryEntry("LDAP://DC=COMPANYDOMAIN,DC=COM", "username", "password");
            object nativeObject = de.NativeObject;
        } catch(DirectoryServicesCOMException) { }

如果我连接到子 OU，它也会抛出the specified domain either does not exist or could not be contacted.

        try {
            DirectoryEntry de = new DirectoryEntry("LDAP://OU=KEE2, DC=COMPANYDOMAIN,DC=COM", "username", "password");
            object nativeObject = de.NativeObject;
        } catch(DirectoryServicesCOMException) { }

我可以使用LDAPADMIN GUI 工具连接并查看 AD 中的结构：

ROOT
  OU=KEE2
  OU=KEE
  OU=other..

我在这里做错了什么？