Problem: Edges have uninitialized flow after setting flow direction
After setting the flow direction with the Set Flow Direction command on the Utility Network Analyst toolbar, there are edges with uninitialized flow, where flow direction is expected.
Uninitialized flow direction in a network occurs in edges that are isolated from the sources and sinks in the network. This can happen either if the edge is not topologically connected through the network to the sources and sinks, or if the edge is only connected to sources and sinks through disabled features.
Solution or Workaround
Display the flow direction arrows so that the uninitialized flow and indeterminate flow symbols differ from each other. <a href='http://support.esri.com/en/knowledgebase/techarticles/detail/26022' target='_blank'>How To: Identify edges with uninitialized and indeterminate flow in a geometric network</a>
Zoom to the location where an edge with determinate flow and an edge with uninitialized flow seem to meet.
Using the Identify tool, examine the junction between the two edges and the edge with uninitialized flow. If the Enabled field value is False for either of these features, then flow cannot pass through these features. Using the Editor in ArcMap, change the Enabled field value to True and set the flow direction again.
If all of these features have an Enabled field value of True, these features are may not be connected to each other. With the editing tools, snap all edge endpoints to the junction to ensure that all edges are connected to the junction. Run the Find Path trace task to ensure there is connectivity through the junction, then set the flow direction again.