Load plugin scripts and styles only on plugin page

Hello wordpress users,

I’m stuck with a problem while running 2 self made WordPress plugins.
I’ll use the following code :

define('PLUGIN_URL', plugin_dir_url( __FILE__ ));
add_action( 'admin_enqueue_scripts', 'plugin_load_js_and_css' );

function plugin_load_js_and_css() {
        wp_register_style( 'plugin.css', PLUGIN_URL . 'plugin.css', array());
        wp_enqueue_style( 'plugin.css');

        wp_register_script( 'plugin.js', PLUGIN_URL . 'plugin.js', array('jquery'));
        wp_enqueue_script( 'plugin.js' );
    }
}

But it’s loading this stylesheet everywhere in the admin panel.
Now I found this in the codex:

function my_enqueue($hook) {
    if( 'edit.php' != $hook )
        return;
    wp_enqueue_script( 'my_custom_script', plugins_url('/myscript.js', __FILE__) );
}
add_action( 'admin_enqueue_scripts', 'my_enqueue' );

But this code is not working for my..
Does anyone have a another option? Or maybe know why it’s not working for me?

When you register a plugin option page you get a hook from the registration function:

$hook = add_menu_page(
    'T5 Demo',        // page title
    'T5 Demo',        // menu title
    'manage_options', // capability
    't5-demo',        // menu slug
    'my_render_page'  // callback function
);

Use this hook to enqueue the scripts and styles:

add_action( "admin_print_styles-$hook", "my_enqueue_style" );
add_action( "admin_print_scripts-$hook", "my_enqueue_script" );

See my plugin T5 Admin Menu Demo for an example.

Do not define a constant PLUGIN_URL. You will run into collisions with other code.