tab name error

hello there, my problem is that since few days ago i have noticed that the name in the browser’s tab stay always the same, it says ‘Header’, no matter which page of my blog the browser is displaying, the tab’s name always stay the same.
It was not like this, but probably tweaking the theme i have modified something.
any help?

ps, i use WP 2.9.2 / Kubrick Theme

blog url: https://www.marcellosimeone.com/blog