Thank you for the reply.
It's necessary to make clear that I am in China and I cannot visit Packal.org directly.(I really do not know that why my country would block this cool website without any politics topics), so I use ShadowsocksX to visit Packal for workflows(thanks for developers for making good stuff). With Shadowsocks I can use Packal search workflow as other users except Packal Updater, which annoys me.
Please see the picture below if anything helps:
I typed "packal" and click the force update but nothing came out except the updating notification, also I could monitor some net traffic through iStatus Menus.