Can’t enqueue scripts in the footer?

Where did you put your code ?

1. the “true” arguments goes in the wp_register_script();, not the wp_enqueue_script() ;

the functions is:

<?php wp_enqueue_script('handle', 'src', 'deps', 'ver', 'in_footer'); ?>

meaning

    <?php wp_enqueue_script('NameMySccript', 'path/to/MyScript', 
'dependencies_MyScript', 'VersionMyScript', 'InfooterTrueorFalse'); ?>

E.G.

<?php
wp_enqueue_script('my_script', WP_CONTENT_URL . 'plugins/my_plugin/my_script.js', array('jquery', 'another_script'), '1.0.0', true);
?>

2. does your theme have <?php wp_footer(); ?> at the end of the page ?

3.add the action with add_action('wp_print_scripts', 'your function');

That being said , your best practice would be :

<?php  
if (function_exists('load_my_scripts')) {  
    function load_my_scripts() {  
        if (!is_admin()) {  
        wp_deregister_script( 'jquery' );  
        wp_register_script('jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js');  
        wp_enqueue_script('jquery');  
        wp_register_script('myscript', bloginfo('template_url').'/js/myScript.js'__FILE__), array('jquery'), '1.0', true );  
        wp_enqueue_script('myscript');  
        }  
    }  
}  
add_action('init', 'load_my_scripts');  
?>  

or add_action('wp_print_scripts', 'dl_register_js');