lightbox for "add an item" and "tell a friend"

Hello! I have problems with these 2 features... it shows only a little box with a X to close, nothing inside. Like the image:


The lightbox of the cart works well:


How can i fix this? Thank you!

I have joomla 3.4.5 - Virtuemart 3.0.10 - Last version template

Seems like Virtuemart -> Configuration -> Templates -> Use Fancybox is unchecked, please enable it.

Correct, now it works like a charm. Thank you!

One more question while i'm here... is there a way to add a "up arrow" and "down arrow" in the products page to add and remove number of items near the "add to cart" button?

Thank you again,

Gianluca

Only by adding this functionality on your own .