No title displayed for header position module - css bug ?

Hi
on my J!2.5 website, when I place a module at header position with configuration set to display the title of the module, it is not displayed
is it a css error or a misconfiguration due to my website ?
on the website Virtuemart featured products are set to this position but the title "featured products" is not displayed whatever I try
http://www.cgigraphicdemo.fr/expovisions/index.php?option=com_virtuemart&view=category&virtuemart_category_id=10&categorylayout=0&Itemid=117
thanks for any help

To bypass the problem I created a new custom module with content "Featured products"
then placed it at Header position too but ordering it before VM module.
I customized custom class (.custom css) to my needs
doing that it looks like the custom module content is the featured product title.