Virtuemart doesn't save Child's attibutes

[ishtarmonique]

There's a problem with custom fields, I created a product and 2 child products, when I try to add a new custom field to their products virtuemart doesn't save them.
   
                        PRODUCT
                               |
                 _______________   
                 |                            |
            CHILD1               CHILD2
           Attribute 1          Attribute 1
           Attribute 2          Attribute 2

I need the Childs to have different types of attributes, so the client can chose "Child 1" and then the "atribute 1, 2" or chose the "Child "2 and then chose the "attibute 1,2"
When I attached those attributes in a "Child" virtuemart doesn't save them.

What can I do? 

Thanks for your help!