Everytime I want to create a null structure I have to shut down my drawing
and re-open it before the null structure will appear in my structures list
of the Network Layout Tools toolbar. Now instead I just use any structure
that is available in my list then in my toolspace Pipe Network Stuctures I
change it's style to Null. Why would my Null Structure not be available in
the list unless a drawing re-start? I use Null Structure mainly to make a
break in my pipe run for a service line.