VMAX port login issue

When adding all the ports into SAN, one port cannot be recognised with Node Name & Port Name. It showed "NULL" as below. Does anyone know the reason? Thanks.

[root@oc4777208076 ~]# symaccess -sid 000198700498 list logins -dirport 2E:1

Symmetrix ID            : 000198700498

Director Identification : FA-2E

Director Port           : 1

                            User-generated                      Logged On

Identifier       Type  Node Name        Port Name        FCID   In     Fabric

---------------- ----- --------------------------------- ------ ------ ------

10000000c9bb31a2 Fibre 10000000c9bb31a2 10000000c9bb31a2 643400 Yes    Yes

10000000c9bb31a3 Fibre 10000000c9bb31a3 10000000c9bb31a3 643500 Yes    Yes

10000000c9bb31a4 Fibre 10000000c9bb31a4 10000000c9bb31a4 642400 Yes    Yes

10000000c9bb31a5 Fibre 10000000c9bb31a5 10000000c9bb31a5 641c00 Yes    Yes

10000000c9bb33c2 Fibre 10000000c9bb33c2 10000000c9bb33c2 7d8580 Yes    Yes

10000000c9bb33c3 Fibre 10000000c9bb33c3 10000000c9bb33c3 7d8380 Yes    Yes

10000000c9bb33c4 Fibre 10000000c9bb33c4 10000000c9bb33c4 642900 Yes    Yes

10000000c9bb33c5 Fibre NULL             NULL             5e80c0 Yes    Yes

10000000c9d1ca6a Fibre 10000000c9d1ca6a 10000000c9d1ca6a 642600 Yes    Yes

10000000c9d1ca6b Fibre 10000000c9d1ca6b 10000000c9d1ca6b 5e8fc0 Yes    Yes