Nonce error: It looks like you don't have permission to do that.

So more problem: When a user does not login or just a visitor, when they try to ask a question and hit “Registrar/Login and submit”, it return this error message:

Nonce error: It looks like you don’t have permission to do that.

But when just answer a question as not login visitor, and hit the same “Registrar/Login and submit” button, they are correctly forward to my registrar page which is a Page using Buddypress registrar Page template.

What went wrong?