Hello
My apologies for the late reply.
Indeed, you can't append network features to the open diagrams in the following situations:
- There are unsaved edits
- The All Layers mode is not turned on on the diagram map to which you want to append new network features
- This diagram is based on a template that doesn’t allows to extend diagrams
- The diagram is historical and is considered as read-only
- Another limitation is when working with a database connection to a utility network in an enterprise geodatabase; the Append to Diagram command only applies to a network diagram layer that is from either a network in a file geodatabase or a utility network service.
You must make sure that you are out of all these situations
Thanks
