l got this error message when trying to start karel program:

Java Code:
Exception in thread "main" java.lang.NullPointerException
	at acm.program.Program.main(Program.java:917)
	at stanford.karel.Karel.main(Karel.java:202)

Java Code:
CODE:
import stanford.karel.*;


public class CollectNewspaperKarel extends SuperKarel {

	public void run() {
		   move(); 
		   turnRight(); 
		   move(); 
		   turnLeft(); 
		   move(); 
		   pickBeeper();
	}

}