Curtain Wall Panel Template - Reporting Parameter Error

If we attempt to attached a Reporting Parameter to a Curtain Panel Template we might see this error message.

It's the result of attaching the dimension to the reference level in the view.

If we are careful to attach the dimension to the reference plane that is lurking underneath it (the reference level) the reporting parameter will attach without complaint. I pulled the Level and the reference plane apart a bit so they can be seen more easily in the image.