Problem to export biped model with extra bones

I made the biped model with extra bones.
I exported it to FBX, but I can’t act with extra bones.
Animation with biped bones was acted.
But animation with extra bones didn’t be acted.

When i export FBX from max file and then import FBX file, animation with extra bones didn’t be acted.

Thank you for your attention.
Help me!!!

the problem doesn’t come from 3dMax,
in Unity, select your character model and in property go to rig panel,
set it to be “Legacy”, and it will solve your problem.