javascript - Jqueryui setdate not setting correct date -

i'm using rails jqueryui datepicker.

$('#rfq_due').datepicker(dateformat: 'mm/dd/yy') 

i have button that's supposed set date 7/13/2015 button sets 08/14/2015 instead.

<a onclick="$('#rfq_due').datepicker('setdate',' 07/13/15');return false;" class="btn btn-default" href="#">1</a>