diff --git a/VolumeSeries.cc b/VolumeSeries.cc
index b0c81efd8ba7b767bfa7bc54c3687ece7d79792b..ef00cfacb7412ba5878e8b3e80a9939bc2c374b4 100644
--- a/VolumeSeries.cc
+++ b/VolumeSeries.cc
@@ -88,12 +88,21 @@ namespace TACO {
 
        preThresholdPositions.ReSize(numSeries);
        
-       float m = 0;
+       float m = 0,s = 0;
        for(int i = 1; i <= numSeries; i++)
 	 {
 	   m = MISCMATHS::mean(getSeries(i));
-	   
-	   if(m > thresh)
+	   s = MISCMATHS::var(getSeries(i));
+	   /*
+	   if(m > thresh && s == 0.0)
+	     {
+	       cerr << "m = " << m << endl;
+	       cerr << "s = " << s << endl;
+	       cerr << "i = " << i << endl;
+	       cerr << "j = " << j+1 << endl;
+	     }
+	   */
+	   if(m > thresh && s > 0.0)
 	     {
 	       j++;	
 	       preThresholdPositions(j) = i;