At the site has www.joomla.org Virtue Mart 1.1 9 for Joomla 2.0 here and on your site do not. Can you explain why? see http://joomlacode.org/gf/project/vm11j25/frs/
That is an unofficial release, made for users who have existing VM1.1.9 complex product setups or special addons to enable them to upgrade to Joomla 2.5 as an interim measure and take more time to develop their VM2 store for J2.5 and future Joomla versions. See http://forum.virtuemart.net/index.php?topic=99339.0
It is supported on http://joomlacode.org/gf/project/vm11j25/forum/