Problem with pose transitions

I am working on an animated jack-0-lantern and am having difficulty with pose transitions.

In the basic rig, I have created shape keys and corresponding poses for jack’s eyes. There are poses for Center, Right, Left, etc. so that I can have him look in all directions. When I create the poses based on the bone locations, the animation is very clean.

The problem occurs after I created a “new shape from mix” of the original “evil” eye to a “surprised” eye. I then created additional shape keys off of the new eye shape for the same eyeball movements as with the original eye shape.

When I create the poses, the transition between poses always deforms the shape of the eye while the eyeball is moving, such as in the following example.

Keyframe, eyes center set

The transition between keyframes deforms the shape of the eyes.

Keyframe, eyes right set

This only happens to shape keys that are made from “new shape from mix”. In each shape key with the eyeball movement, the only thing that changes is the location of the eyeball so I don’t know why it is also changing the shape of the eye.

I am still fairly new to Blender and have been following the tutorials and videos but obviously there is quite a bit about animation that I need to learn.

Any ideas?

Thanks - M