Only VIs inside the same library or libraries as the private library item can access the item.
To correct this error for a project library, change the access scope of the library item that you are trying to reference. You can also remove the library item from its owning library by right-clicking the library item and select Remove From Library from the shortcut menu.
You only can create protected library items inside LabVIEW classes, and you only can access the protected library items from inside the same LabVIEW class or LabVIEW classes inheriting from that class.
To correct this error for a LabVIEW class, change the access scope of the member of the class that you are trying to reference.