Hi Keith
The error message means the structure is not correct.
I would first recommend checking out the "Intro To SVG and PSD Workflow" tutorial on the Courses page below which explains the changes made in version 5.1.
https://courses.reallusion.com/home/cartoon-animator/pipelines-and-render/illustrator/Then depending on if your character is a FreeBone character or a Standard G3 Character check out the two tutorials below.
Setup Your Favorite SVG Editor as Content Creator (FreeBone)
Creating a G3 SVG Character in Illustrator | Cartoon Animator 5 Tutorial (G3 Character)
Overall if you are new to character creation in CTA5, it is strongly advised to start using the supplied Templates which will give you the correct structure to start with and then you only have to switch the artwork to your own. However, once everything is clear and you understand the required structure, you can begin building your characters totally from scratch.
Peter
Forum Administrator
www.reallusion.com