How to parse extensions in Router?

I'm trying to parse URL like this:
`/shops/4/eng/categories/22,skin-care.html`

So I put this router rule:
{{{
Router::parseExtensions('html');
Router::connect(
'/shops/:shop_id/:locale/categories/:id,:slug',
array('controller' => 'categories', 'action' => 'view'),
array('pass' => array('id'), 'shop_id' => '[0-9]+', 'locale' => '[a-z]{3}', 'id' => '[0-9]+', 'slug' =>