Index: BH13SPARQLBuilder/src/hozo/sparql/gui/SparqlBuilderPanel.java
===================================================================
--- BH13SPARQLBuilder/src/hozo/sparql/gui/SparqlBuilderPanel.java (revision 44)
+++ BH13SPARQLBuilder/src/hozo/sparql/gui/SparqlBuilderPanel.java (revision 54)
@@ -329,5 +329,7 @@
 public String createSPARQL(Path path, int num) throws Exception {
 		
-		
+		if( path == null ){
+			throw new Exception("Path is null.");
+		}
 		String startClass = path.getStartClass();
 		List<ClassLink> classLinks = path.getClassLinks();