rating stars inactive (but showing)

[canalejas]

Hi all, I have a problem with rating stars to take a vote of a product. When I pass the mouse over the stars do not change, always stays at 5. It seems as if some plugin was disabled but does not seem so from what I have seen. This I worked at first, but has stopped working.
Not if it can be related but I recently installed an extension called VMVendor to convert in multivendor VM2.
I would appreciate if someone can give me any idea how to find.
Thank you very much.
Working with: Joomla 2.5 and VM2 (with the adaptation of VMVendor 1.3b)