How to Activate WordPress Widgets

If I understand correctly, the issue you’re facing is that the widgets aren’t showing up when they’re populated.

This is caused by the php if statement you’re using not containing an else argument. If you change your code to look like below, it should work.

<header class="fix header_top_area">
    <div class="fix container header_top">

        <?php if (!dynamic_sidebar('header_top')) : ?>

        <div class="fix floatright header_top_text">
            <div class="fix floatleft call">
                <p>Chicago, USA,  Call : 00 000 0000</p>
            </div>

            <div class="fix floatleft sign_in">
                <a href="">Sign In</a>
            </div>
        </div>

        <?php
            else :
                dynamic_sidebar('header_top');

            endif; 
        ?>

    </div>
</header>

<header class="fix header_bottom_area">
    <?php if (!dynamic_sidebar('header_bottom')) : ?>

    <div class="fix container header_bottom">
        <figure class="fix floatleft logo">
            <a href="<?php bloginfo('home'); ?>">
                <img src="<?php bloginfo('template_url');?>/img/logo.png" alt="" />
            </a>
        </figure>

        <figure class="fix floatright image_header">
            <a href="">
                <img src="<?php bloginfo('template_url');?>/img/image_header.jpg" alt="" />
            </a>
        </figure>
    </div>

    <?php
        else :
            dynamic_sidebar('header_bottom');

        endif; 
    ?>

The issue with the code you were using was that it doesn’t know what to do is the sidebar isn’t empty. With the code above, when the sidebar is populated, it will show that content.

Let me know if that doesn’t work for you.