I cannot find out how to create a subpart. I have followed the tutorial [https://docs.easyeda.com/en/SchematicLib/SchLib-Create/](https://docs.easyeda.com/en/SchematicLib/SchLib-Create/) word for word but each time when I right click the component in the library, the "Add Subpart" is greyed out. Can I get help on this? Thanks, Michael