The line asset group and asset types provided for Aggregated Lines must be a subset of the values provided for Valid Lines.
When you set the subnetwork definition for the tier for the first time, ensure that the line asset group and asset type values for the aggregated lines are a subset of the valid lines. If you're making modifications to an existing subnetwork definition, review the valid lines for the tier. You can review the valid lines in the network properties for the utility network layer. See Set or modify the subnetwork definition for more information.