Error: Duplicate Custom Navigations

Hi everyone,

hope you can help me out, because I’m stuck with this for almost two days now.

I made a theme with three custom navigations, one in the header, two in the footer. Problem is: when I view the page, all three locations show the same menu and not the attributed ones.

The code for my functions.php is:

function register_my_menus() {
  register_nav_menus(
    array(
      'header' => __( 'Header Menu' ),
      'footer_left' => __( 'Footer Left' ),
      'footer_right' => __( 'Footer Right' )
    )
  );
}
add_action( 'init', 'register_my_menus' );

The code in my footer.php is (the header navigation is positioned absolute):

<?php wp_nav_menu( array('footer_left' => 'Footer Left' )); ?>
<?php wp_nav_menu( array('footer_right' => 'Footer Right' )); ?>
<?php wp_nav_menu( array('header' => 'Header Menu' )); ?>

As far as I can see, the menus are setup properly in the WordPress backend. Any ideas what I am doing wrong here? Any help is appreciated.
Thanks in advance!