plugin not hooking to my custom hook

Question

I am trying to hook my plugin to my custom hook in my header.php but it doesn't seem to work but if i hook to my header through the function.php everything works perfectly. Does anyone have any idea how I can get it to work.

header.php

<?php logo_hook(); ?>

function.php

function logo_hook(){
do_action('logo_hook' );
echo 'function is working';
}

logo.php //this is my plugin

add_action( 'logo_hook', 'displayLogo');
function displayLogo( $text ) {
        $logo .= 'Plugin text...';
        return $text ;
}

Answer 1

You should using do_action in your header.php

do_action( 'logo_hook' );

And adding a value on this section with below function:

function add_text() {
    echo 'Hello world!';
}
add_action( 'logo_hook', 'add_text' );