[solved] Blank map on product details

I've tried editing the product with firefox and chrome in Debian after saving a backup of the mysql data and the map disappeared.
i've compared the 2 sql and i've found that in my sql saved data there is no customfield_value: vm2geolocator .
So i setted up vm2geolocator in customfield default values and now it works when want to add a map in all the products.
However i wanted to go deeply and i've tried removing that value in the defaul setting .. still not working ; the form in the admin area have empty value in the customfield_value form field.. Tried add manually with firebug and after saving the map appear because that value has been saved in mysql.
My suggestion is to add that value directly in the script so there will be no possibility that a customer will not find it if it is not saved in default values. Sorry my bad english, i appreciate if you can tell me what you think about it.
Mauro

Thanks for your investigations, but I'm not sure I fully understand. What do you exactly recommend?

I don't know exacly, i need to study your code and maybe i can give you an idea. The main problem is that in the page where i can setup your plugin , for me "administrator/index.php?option=com_virtuemart&view=custom&task=edit&virtuemart_custom_id=4" , there is not the default value "vm2geolocator" . So if a customer that don't know that is a requested field could delete it.
Mauto

I understand but there are actually default values (50,3)
set in the xml.