C# 将子项添加到EntryDirectory错误

当我想添加目录时，我通过ldap连接连接到linux系统 我在将子项添加到EntryDirectory时遇到问题， myDirectoryEntry.CommitChanges（）；有例外

static void Add(DirectoryEntry entry)
    {
        DirectoryEntries myEntries = entry.Children;
        DirectoryEntry myDirectoryEntry = myEntries.Add("AccountNumber=3", "simpleSecurityObject");
        myDirectoryEntry.Properties["sn"].Value = 3;
        myDirectoryEntry.Properties["firstname"].Value = "test name";
        myDirectoryEntry.Properties["lastname"].Value = "test family";
        myDirectoryEntry.CommitChanges();
        entry.CommitChanges();
        Console.WriteLine(myDirectoryEntry.Name + " entry is created in container.");
    }

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什么异常？@ChetanRanpariya System.DirectoryServices.dll中发生类型为“System.DirectoryServices.DirectoryScomeException”的未处理异常。其他信息：请求的操作未满足与对象类关联的一个或多个约束