Create new Code Template, + button grayed out

I'm trying to figure out how to create a new C++ code template (something like a comment for sectioning off portions of a large cpp file), however I'm finding that the plus button for 'Creating a New Template' is grayed out and I can't make a new one. Please see attached screenshot. Is this unexpected behavior, or am I misunderstanding the process for adding a new, reusable piece of C++ code?

Thanks,
Rich