Problems Saving Templates

Attempting to save multi layered graphics as templates- templates do not save. This latest design was originally created last year in AE. I have duplicated the original and want to create a template. I'm working at a school, trying to get teachers on board with libraries and templates this term. Myself and the teachers most often get this error (I think I've only had one or two save correctly). I have been attempting this on and off for months now in both new and old version of AE.