Free shipping issue

Hello,

On my website some product have free shipping and some have paid shipping. So i created a “free shipping” shipping class. But when a product with this shipping class is added to the cart, instead of showing “shipping 0.00”, it just shows “shipping” (with no price). If i set the price to O.01 it shows “0.01” but if i set it to “0” or “0.00” it just shows nothing after.
How to fix that ? How to let customer know that shipping is free ?

Thanks for your help

The page I need help with: [log in to see the link]