This code works perfectly for me:
add_action( 'admin_head', 'my_icons' );
function my_icons() { ?>
<style type="text/css" media="screen">
#menu-posts-product .wp-menu-image, .icon32-posts-product {
background: url(<?php echo get_template_directory_uri(); ?>/img/contactLensemenu.png) no-repeat center center!important;
}
#menu-posts-product .wp-menu-image { background-size:16px 16px!important; }
.icon32-posts-product { background-size:32px 32px!important; }
</style>
<?php } ?>
PHP part is the same of the yours, (except for get_template_directory_uri()
that I use for convenience, because it is equivalent to your /wp-content/themes/BootWp`)
I changed a bit the css, but I down know dimension of your image, the mine is 64X64px.
My WP is 3.6 and the product post type is registered by WooCommerce.