Thanks Stephen for your reply.
I'm really newbie on PHP, plus my english is not so good and maybe i don't understand something from the pages you linked.

Basically:

I've got this module/component, called MagicZoom, and it should work only on some Virtuemart category products details.

I installed the mod_metamod module, i enabled it and disabled the menu assignment. I set the position as the MagicZoom module.

Then i wrote that on PHP form:

$vm = JomGenius("virtuemart");
if ($vm->check("category_ids = 18, 19, 20")) return 60;

// replace XXX with the module id to use on categories 4, 5 and 6

I replaced the ID from categories and modules as well, and obviously nothing changed.

NOW: How i can disable the module on all the other categories??

Thank for your patience.
M.

thank you stephen!!!
i've done what you said and it works now.
really apprecciate your help.
great module!
cheers
m.

Please check the FAQs.

http://www.metamodpro.com/metamod/faq