Oh, Thank you very much for the answer!
I didn’t know root bone thing is the solution.
I also bought my chracter(skeleton mesh), I guess It doesn’t have root bone.
(If I turn on root bone checkbox in Animation BP in UE4, my character doesn’t move forward in the BP window. He swims in the air…)
I’m very newbie to 3d tool such as 3ds max things, I guess I open it up in the editor, and add ‘root bone’ on the top of my ik bones.
Am I right?
Is the other way to do in UE4? 