unable to echo custom title if page

i have a posttype to which i have a page templates assigned using plugin custom posttype page template, so that my posts having img attachments in the posttype are displayed using a particular template. In my header.php i have code

if ( is_page_template ( 'page-book.php' ) )
				{ $currenturl=$_SERVER['REQUEST_URI'];
				  $booktitle = str_replace("https://mybooks.com/books/", "", $currenturl);
				  $booktitle = str_replace("-", " ", $booktitle);
				  $booktitle = strtoupper($booktitle);
				  echo $booktitle;
				}

but it echoes the url of the post in the title instead of the custom echo

how do i get it to echo the custom title