Shortcode not showing anything

I am using this code, but nothing is being shown on the front page. It seems the shortcode is registered correctly though.

function choose_ashtopbar() {
?><img src="/images/flag_globe2.png" class="ttupmg" /><div class="dmzeus"><ul><li class="f-selection">London<ul><li>New York</li><li>Paris</li><li>Milan</li></ul></li></ul></div><?php
}

function register_ashcodes(){
add_shortcode('ashtopbar', 'choose_ashtopbar');
}

add_action( 'init', 'register_ashcodes');

via Chebli Mohamed