After Apply IK Spline to joints (joints are following the z direction, horizontally oriented), and then skin the spline curve to 2 new separate joints, the new joints can only move the curve and joints in x and y direction (like waving) but can not be stretched following the z direction. I was following the steps in this youtube instruction: https://www.youtube.com/watch?v=qBxtDFdWBhw. What setting did I miss?
