Hi Sean, that was super helpful. Many thanks. The error returned a null pointer for the shape file, which led me to adjusting my path reference, and it worked. Thanks again.

MASON Version 19.  For further options, try adding ' -help' at end.
Starting to read shapefiles...
Exception in thread "Thread-0" java.lang.RuntimeException: Exception occurred while trying to construct the simulation class model.HedgeVax_Controller
	at sim.engine.SimState$1.newInstance(SimState.java:366)
	at sim.engine.SimState$2.run(SimState.java:610)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
	at java.lang.reflect.Constructor.newInstance(Unknown Source)
	at sim.engine.SimState$1.newInstance(SimState.java:361)
	... 2 more
Caused by: java.lang.IllegalArgumentException: shpFile is null; likely file not found
	at sim.io.geo.ShapeFileImporter.read(ShapeFileImporter.java:241)
	at sim.io.geo.ShapeFileImporter.read(ShapeFileImporter.java:197)
	at model.HedgeVax_Controller.readData(HedgeVax_Controller.java:37)
	at model.HedgeVax_Controller.<init>(HedgeVax_Controller.java:27)
	... 7 more