Hi,
What is your Joomla version? If your Virtuemart is 2.6.12, then you must be using Joomla2.5.xx
Fancy Product Slider comes with 2 Installation ZIP file:
1 - for Virtuemart 2.x (compatible with Joomla2.5.x)
2 - for Virtuemart 3.x (compatible with Joomla3.3.x)
Please install the appropriate ZIP file.
Regards.