Another drop down menu problem (header k2)

My problem is the following:

My blog http://www.getlow.es , has in his header section a menu bar were you will se one called “coches de invitados” , “bricos” , …

Well in the one called “bricos” it should came on a dropdown menu, whit 2 sections, for example: http://www.getlow.es/bricos/electronica-20vt-en-golf-mk2

The problem is: When I came over whit the cursor or just click on “Bricos” no dropdown menu is shown, So I read a few posts were people talks about Z-something wich should be put up to 999, so the menu appears in front, but no way…

Need some help.

Thank you.