Hi Bambang,

you have two options:

1. Publish login module or add login view into menu, - then login (in demo front-end it should be here: Pages > login)
2. OR, in Joomla Admin, Global Configuration > System > Shared Sessions: Yes

Shared by you login details doesn't work, so I cannot login as well (in admin area). But just listen my advices. 2nd option is easy and always works.

Thanks Paul,