diferent header for blog page (UNICON theme)

Hello,

I want to have diferent header for evry post on theme UNICON, but theme doesn’t support it: https://preview.themeforest.net/item/unicon-designdriven-multipurpose-theme/full_screen_preview/10648488?_ga=1.59256941.1112640924.1467826143

I try whit: https://www.templatemonster.com/blog/add-different-headers-in-wordpress/

I first create php file (blog_header) with header code and change it for blog header

And then call in page.php

`<!–?php
if(is_post()) {
get_header(‘blog_header’);
}
else {
get_header(‘header’);
}
wp_head();
?–>

And it doesn’t work

Can anyone please help me?

Thanxs,

A