The reviews star rating score was firstly shown on the product page. After I've changed the default rating ( I translate Price into Dutch and deleted Quality and Value) the star ratings isn't shown on the product page. Hereby the code and I noticed the no-rating part:
<div class="product-reviews-summary **no-rating**" itemprop="aggregateRating" itemscope="" itemtype="http://schema.org/AggregateRating">
How can I show the star rating again?