RichSnippets for Reviews - Error: Incomplete microdata with schema.org

Question

I tested it with the Google tool (http://www.google.com/webmasters/tools/richsnippets) and it shows me an error (Error: Incomplete microdata with schema.org).

<p itemprop="review" itemscope itemtype="http://schema.org/Review">
  <em itemprop="author">
    Walter
  </em>
  :
  <span itemprop="description">   " I just love this product and I'll always buy this one" </span>
  <br>
  <br>
</p>
<p itemprop="review" itemscope itemtype="http://schema.org/Review">
  <em itemprop="author">
    Jesse
  </em>
  : <span itemprop="description">"I don't think I'll buy it again and recommend it to others."
  </span>
  <br>
  <br>
</p>

Should a review contain everything? What am I missing?

I looked up http://schema.org/Review and my sample seems to be aligned with the example. I'm new to this and I could use some pointers.

Answer 1

Silly me! I didn't read Google guidelines fully. As per https://support.google.com/webmasters/answer/146645, I am missing required attributes.

itemreviewed(item) and rating are required for aggregated reviews and mine has none.