Finally! It works, i just have to change right calculation method (with / or without taxes, shipping...) to show the real margin and it works!
Really appreciate your time to help me, can i send you some beer? Paypal for ex. ?
Here is the final view.tpl code to show this:
{foreach from=$order->getOrderMargin() item=orderMargin} {if $orderMargin.id_order == $order->id} <div class="panel"> <h3>Order Margin Information</h3> <p>Margin: {displayPrice price=$orderMargin.total_paid / 1.2 - $orderMargin.total_supplier_price - $order_shipping_price / 1.2}</p> </div> {/if} {/foreach}