使用LDAP连接方法连接LDAP C＃时出现无效凭据错误

Question

LdapConnection ldapConnection = new LdapConnection("abc.com:636");

var networkCredential = new NetworkCredential(UserName,Password,"ou=users,dc=nonproduction");
ldapConnection.SessionOptions.SecureSocketLayer = true;
ldapConnection.SessionOptions.VerifyServerCertificate += delegate { return true; };
ldapConnection.AuthType = AuthType.Negotiate;
ldapConnection.Bind(networkCredential);