Couple issue with ragdolls

Trying to have one skeletal mesh hold the neck of a ragdoll for an animation. Firstly I can almost get the physics constraint in the blueprint working, connected by the root bone. But it stops working when I enter the names of the bones intended to be connected and just drops the ragdoll. I know I put the bone names in correct order too.

Also, the ragdoll flips out with physics and changing mass, linear damping, and angular damping, even to extremely high numbers, changes nothing. How do I get the constraint and damping working?