diff -u -r1.11 -r1.12
--- SensorOccupancyPlotsDriver.java	8 Apr 2012 23:48:12 -0000	1.11
+++ SensorOccupancyPlotsDriver.java	13 Apr 2012 00:06:55 -0000	1.12
@@ -26,7 +26,7 @@

  * as the number of sensors, and hence plotter regions, is hardcoded to 20.
  * 
  * @author Jeremy McCormick <[log in to unmask]>

- * @version $Id: SensorOccupancyPlotsDriver.java,v 1.11 2012/04/08 23:48:12 jeremy Exp $

+ * @version $Id: SensorOccupancyPlotsDriver.java,v 1.12 2012/04/13 00:06:55 jeremy Exp $

  *
  */
 public class SensorOccupancyPlotsDriver extends Driver implements Resettable {

@@ -165,7 +165,8 @@

     }
 
     public void endOfData() {

-    	plotter.hide();

+        if (plotter != null)
+            plotter.hide();

     }
     
     public void reset() {