Error Incomplete microdata with schema.org

Hi, does anybody know why I get the error: Incomplete microdata with
schema.org

Rich snippet tool:
http://www.google.nl/webmasters/tools/richsnippets?q=http%3A%2F%2Ftoolsetbootstrap.wpplayground.wpengine.com%2Fmin-and-max-price-not-working%2F

Kind regards,

Willem-Siebe

Received on Monday, 12 August 2013 16:30:58 UTC