To perform a network analysis using Arcview Network Analyst, a road theme must be present in your View window:
Make the View window active,
View > Add Theme > Select slcroads.shp
Repeat this for the following themes: facilities.shp, events.shp, stops.shp
The first time you perform a network analysis on a line theme, Arcview Network Analyst will build the topology, create a cost matrix and then run the analysis. In a large network, this may take some time. The next time you run an analysis on the same network, the topology is then already present, and the analysis runs much quicker. However, as soon as you edit the theme attribute table, Arcview Network Analyst will have to rebuild the topology again before running any analysis.