I see that your css reference is not complete version (seems to be partial); try change your include reference in the following:
http://cdnjs.cloudflare.com/ajax/libs/qtip2/2.1.1/jquery.qtip.js
http://cdnjs.cloudflare.com/ajax/libs/qtip2/2.1.1/jquery.qtip.css
It's partial because is the js/css Basic features
version (no additional styles or features) you must use the All features & styles
.
Download page: http://qtip2.com/download