Bug: Connectivity rules cannot be added or removed from a geometric network
When using ArcGIS 10.x, connectivity rules cannot be added or removed from a geometric network. This issue is exposed through adding connectivity rules through the geometric network property page or through adding connectivity rules through the geoprocessing tools.
This issue is due to NIM079465.
The only workaround for this issue is to use ArcGIS 10.1 SP1 to add/remove connectivity rules, as it contains the fix for NIM079465.