The problem is caused by loading lower jQuery version that Yootheme prerequisite.
- YOOtheme requires +jQuery1.7 (jQuery1.7 or higher)
- Virtuemart loads jQuery1.6.4 by default.
If you carefully read the topic i gave you above, i provided solutions try them to resolve this conflict. It doesn't matter the add to cart button starts working. IT is always bad the leave the website with the conflict issue. That is a serious problem and must be resolved. It will give you some headache some other time eventually.
about
www and
non-www thing. This is a Virtuemart Component bug (not our Templates) and it has been also discussed in this forum. Read below for permanent solution:
www.flexiblewebdesign.com/forum-joomla-virtuemart-template-lightmart-support/1983-the-cart-does-not-add-any-items-in-browser-when-th#9071
Regards,
Support