UserPrincipal的新实例（PrincipalContext）返回Null

Question

我在构造函数中有一小段代码：

public class ADUser : ADObject
{
    public ADUser(PrincipalContext ouContext)
                : base(null)
    {
         ou = ouContext;
         // Even after instantiating, user remains null, which is where the problem lies.
         user = new UserPrincipal(ouContext);
         base.principal = user;
    }
}

public abstract class ADObject
{
    protected Principal principal;
    protected PrincipalContext ou;

    public ADObject(Principal principal)
    {
        this.principal = principal;
    }
}

ou是基类中的受保护变量，用于存储正在修改或创建的AD用户的AD OU的PrincipalContext。

调试时，参数ouContext 不为空值，但每当我尝试使用它作为参数实例化新的UserPrincipal对象时，user总是结束为空。

以下是ouContext PrincipalContext对象的输出：

-ou {System.DirectoryServices.AccountManagement.PrincipalContext}   System.DirectoryServices.AccountManagement.PrincipalContext
        ConnectedServer "CensoredDC02.CensoredDomain.CensoredParentDomain.com"  string
        Container   "OU=Censored,OU=Censored2,DC=CensoredDomain,DC=CensoredParentDomain,DC=com" string
        ContextType Domain  System.DirectoryServices.AccountManagement.ContextType
        Name    "CensoredDomain"    string
        Options Negotiate | Signing | Sealing   System.DirectoryServices.AccountManagement.ContextOptions
        UserName    null    string

使用以下代码在另一个类中创建PrincipalContext对象：

/* baseDomain has the FQDN the OU is in, and ouSelection contains the full DN path of the OU. */
ouContext = new PrincipalContext(ContextType.Domain, baseDomain, ouSelection.SelectedValue.ToString());
/* Then a new ADUser object is created... */
ADUser user = new ADUser(ouContext);
/* Shortly after, the null value returned by new UserPrincipal(ouContext) causes an exception to be thrown in another function. */

提前感谢您的帮助！