Wont display repeater fields

I am trying to make a custom header with ACF, but for this header I need menu items and those menu items need sub items. I have 2 repeater fields one inside the other. But when I try out the code it does not work. But I do not get a error or something like that so I do not know where it goes wrong! Can somebody help me please!

I tried to display it by using this code:

// check for rows (parent repeater)
                if( have_rows('header_menu') ): 

                    // loop through rows (parent repeater)
                    while( have_rows('header_menu') ): the_row(); ?>
                            <?php 
                                $linkMenu = get_sub_field ( 'menu_item_link' , 'options' );
                            $tekstMenu =  get_sub_field('menu_item_naam' , 'options');
                            // Do something...
                            ?>
                            <a href="<?php echo esc_url ($linkMenu); ?>">
                                <?php echo $tekstMenu; ?>
                            </a>
            <?php
                            // check for rows (sub repeater)
                            if( have_rows('menu_item_submenu') ): ?>

                                <?php 

                                // loop through rows (sub repeater)
                                while( have_rows('menu_item_submenu') ): the_row();
 
                                    $nestledLink = get_sub_field( 'nestled_item_link', 'options');
                                    $nestledNaam = get_sub_field('nestled_item_naam', 'options');

                                    // display each item
                                    ?>
                                    <a href="<?php echo esc_url($nestledLink); ?>"<?php echo $nestledNaam; ?></a>
                                <?php endwhile; ?>
  
                            <?php endif; //if( get_sub_field('menu_item_submenu') ): ?>
 

                    <?php endwhile; // while( has_sub_field('header_menu') ): ?>

                <?php endif; // if( get_field('header_menu') ): ?>

But literally nothing happens