I think I install this plugin because my forum did not show pm notification.
but i will test it!
Well I had a look at the header template for your theme and a few other things were missing, including the code for the PM notice, but the actual PM alert is wrapped in <noscript></noscript> so it'll only show if javascript is disabled.
wow! That's great. all users view ban warning now!
It's because you've got "Yes, this is a banned group" ticked for the registered usergroup...
user is not ban.
users can post and view thread but show bannig warning
Yes, read what I said; in the settings for the registered usergroup, the "Yes, this is a banned group" option is ticked. I saw it myself, that's how I knew it was ticked... they're not actually banned, but because this option is ticked, it shows this message.
But wrote this: If this group is a 'banned' user group, users will be able to be 'banned' in to this user group.
I can not ban them if i disable it,probably!
That's not what it means, untick that option.
No, this options means this is a group people can be placed into when they are banned, it does not mean that people in this group can only be banned if this option is ticked. It even says there that they will be banned into that usergroup, as in that's a group you can choose to put someone in when you ban them. For your forum, it only needs to be ticked for the actual Banned group.