Exact same problem, facebook, linkedin and twitter are working properly.
The link that redirect to pinterest via addtoany seems to be the problem.
My code :
<li><a target="_blank" class="a2a_button_facebook fb"></a></li>
<li><a target="_blank" class="a2a_button_linkedin ln"></a></li>
<li><a target="_blank" class="a2a_button_pin pin"></a></li>
<li><a target="_blank" class="a2a_button_twitter twitter"></a></li>
The url from addtoany
http://www.addtoany.com/add_to/pin?linkurl=http%5B…%5D
Compare to
http://www.addtoany.com/add_to/twitter?linkurl=http%5B…%5D
Twitter works not pinterest
