Help a little bit with shema org

Hi Blackhatworld Users.
So i will explain how thing are going for my site...
I would like to use shema and currently its all about this:
i ve done this manually with all atributes
<div itemscope itemtype="http://schema.org/Product">
<span itemprop="name">Write My Speech</span>
<div itemprop="aggregateRating"
itemscope itemtype="http://schema.org/AggregateRating">
<span itemprop="ratingValue">4.28</span>
out of <span itemprop="bestRating">5</span> stars
based on <span itemprop="ratingCount">13</span> user ratings
</div>

when i search my site in google like this site:domain.com
the stars appear but if to use keywords in search domain.com pages without stars ( in bing its working well ) but google...
Maybe someone will explain.
Best regards!

google does not guaranteed your schema will be displayed
https://sites.google.com/site/webmasterhelpforum/en/faq-rich-snippets