Blend Shape strange behaviour with rigging

[newtaov]

Hi
I've made a character with blend shape (a smile face) and rigging (full body). Blend shape works fine and rigging works fine, but when I turn the head to the side strange deformations happen to the rigged/blended character smile face. 

The Smile face is blended (paralel) to a buffer model (identical to the rigged model) and this buffer model is blended (paralel) to the rigged model. All facial expressions are blended to the buffer model and only one blend shape (paralel) is blended to the rigged model.
Skin cluster of the head is painted 100% weighted to the Head Joint, so it's not an area influenced by any other joint.

I've tried to change inputs order, but didn't solve. I've tried to turn off all other blends, but didn't solve as well.

Any clue about what's wrong?

[hamsterHamster]

Wait, why parallel? Any reason?

I'd make blendshapes (or its buffer) regular and BEFORE skinning.

[newtaov · Accepted solution]

As usual, I solved myself. I deleted the buffer Blend Shape node and created a new blend shape using Pre-Deformation instead of paralel and it worked.

[newtaov]

I normally use paralel to have independent deformations. But I realize Paralel works very well with all facial expressions connected to the buffer model, but sometimes causes troubles when I connect the buffer to the rigged model.

In fact, the order of Blend Shape and Skin Cluster doesn`t matter that much, because Maya always evaluates the Blend Shapes before the Skin Cluster under the hood, even if it`s not that order in All Inputs.

[hamsterHamster]

Yet, as you just experienced, it is not reliable. I bet for linear+before. Besides, you can fake "parallel" with middle-man blendShape node.