Display Arrows on a geometric network are not displaying any arrows

Description

** Fixed at ArcGIS 8.2 **

With a geometric network added to ArcMap, clicking Flow on the Utility Network Analyst toolbar and clicking Display Arrows does not draw any flow arrows, even though the Display Arrows button becomes inset as if the arrows were drawn.

Cause

There are multiple possible causes for the flow arrows not being displayed in the map. The steps in the Solution section below walk through all the possible causes and how to solve them.

Solution or Workaround

1. Make sure the scale range for displaying flow arrows is appropriate for the current extent.
   <a href='http://support.esri.com/en/knowledgebase/techarticles/detail/21263' target='_blank'>How To: Determine the scale range for displaying flow arrows</a>
2. Make sure that the flow arrows are to be displayed for the appropriate layers. Click Flow > Display Arrows For to examine and set the layers for which flow arrows are to be displayed.
3. Flow arrows do not draw if the current map is being displayed using certain coordinate systems. This is a known problem in ArcGIS 8.1 and 8.1.2. The work-around for this problem is to clear the coordinate system from the current map to display the flow arrows.
   
   This problem has been addressed in ArcGIS 8.2.