FGT1000D: SSL VPN cannot filter mac address

Hi team, 

Please help to check why I cannot use below configuration to filter the user's mac address connect to my FGT?

#conf vpn ssl web portal   edit portal     set mac-addr-check enable     set mac-addr-action allow     config mac-addr-check-rule       edit "rule1"         set mac-addr-list 01:01:01:01:01:01 08:00:27:d4:06:5d         set mac-addr-mask 48   end end