“属性”和"GetProperties“对UserPrincipal不可用，无法获取”部门“和其他值

using System.DirectoryServices.AccountManagement;

// 创建PrincipalContext对象
using (PrincipalContext context = new PrincipalContext(ContextType.Domain))
{
    // 根据用户名查找UserPrincipal对象
    UserPrincipal user = UserPrincipal.FindByIdentity(context, IdentityType.SamAccountName, "username");

    if (user != null)
    {
        // 获取UserPrincipal对象的基础DirectoryEntry对象
        DirectoryEntry directoryEntry = user.GetUnderlyingObject() as DirectoryEntry;

        if (directoryEntry != null && directoryEntry.Properties.Contains("department"))
        {
            // 获取"部门"属性的值
            string department = directoryEntry.Properties["department"].Value.ToString();
            Console.WriteLine("部门: " + department);
        }
    }
}