I deleted all plugins but am leaving “Hello Dolly” and “Tabs Responsive” from the list of plugins on WP and the plugins folder of my server.
Then created a new project called “Add Tabs” . however the problem still exist.
and also the button of “Add Tabs” dose not work now.
The menu of “Add New Tabs” still work.
This is the new project.
http://brzybra.sakura.ne.jp/db/tttt/
I guess, I am also having the same problem.
(test page)
http://brzybra.sakura.ne.jp/db/jport/portj9/