hair deformation not smooth

hair shown in unity, not deforming smoothly when head is rotated slightly..
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hair deforming fine in maya when head rotated..

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any ideas?

 

I did find a clue in my Console today, it said the following error:

ImportFBX Warnings:
Skipping influences for 'Neck' because it is marked as ADDITIVE. This most likely means that you are using a blend shape or custom deformer, which is not supported.
Skipping influences for 'Spine2' because it is marked as ADDITIVE. This most likely means that you are using a blend shape or custom deformer, which is not supported.
Mesh 'head1' has 238 (out of 238) vertices with no weight and bone assigned (they will be assigned to bone #0 with weight 1). The list of vertices: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and so on...

I did some research about it and it mostly occurs because of RIGID skinning type. I was using rigid skinning for the head because no deformation was required.

So as a test I did the following:
saved a copy of my character with no skinning, no keyframes, no history.
selected character, selected skeleton and hit Smooth Bind.
Just as a test, with no further modifications, baked 100frames of bind pose and imported into unity, selected humanoid, it showed the checkmark, I went into Configure and rotated the neck joint and same thing is happening as before. Hair is not stretching right. Does anyone have a suggestion?

 

I also tried taking away the extra joint in the skeleton so that all back bones are auto-mapped into the mecanim. also tried every possible skinning method and weights normalization setting during binding, I also tried setting max influences to 4 down from 5 when binding, no luck the hair weights don't seem to come in correctly to unity.

 

okayyy, I just fixed this finally.. by setting the Project Settings -> Quality -> Blend Weights from 2 bones up to 4 bones.