I found a situation that I don't understand. It seems that the automatic weight painting does not work with the girl that I have rigged using rigify. I don't understand the reasons of this behaviour,because :
1) I'm trying to deform the parts of the mesh that are attached with the DEF bones
2) I'm repeating the steps that I did previously with the boy and it worked
3) I split the mesh into several pieces and I have attached each piece to the rig called "rig.girl" under the armature modifier tab
Let's take as example the bone called "DEF-forearm.L.001". I would like that it deforms the "braccio_sx_girl" aka arm_left_girl. What I do to achieve this output ?
a) I select the bone "DEF_forearm.L.001" ;
b) I press SHIFT and then I select "braccio_sx_girl" ;
c) I change from object mode to weight paint mode ;
d) I do weights / assign automatic from bones ;
but the mesh is not deformed....
NB : I repeated again the steps from "a" to "d" with the boy and it worked.
This is the blender file.