Error Message: Unable to create shell. Try to change spline. During the shell workflow in appliance designer

Error overview

This error usually occurs when the user is attempting to create a shell in appliance designer, however the focal points were not placed in a proper way, reason why the shell cannot be created. 

For the continuation of the creation of the shell there must be at least two focal points on each tooth for better reference for the shell. 

Resolution cause

In order to resolve the issue at least two points were located on each tooth and after that the shell was created correctly. 

After the focal points were positioned correctly the shell was created.