Move vertex along its normal

Hi! In my script I try to move two verteces of a plane along their normal. I obtain a ‘rotation’ of the plane and this is what i want ( I should iterate this for thousands faces in another mesh ). But when i try to apply the script to the other mesh nothing happens.

I use:
mesh.vertices[i].co+=mesh.vertices[i].normal*x

Can’t understand why using this on blender’s python console it works fine
Tips?

Problem solved! vertices do not have normal until faces are set.

All vertices have normals without any edges/faces.