diff -u -r1.20 -r1.21
--- LCDDDetector.java	12 Mar 2008 23:21:05 -0000	1.20
+++ LCDDDetector.java	15 Sep 2009 00:57:04 -0000	1.21
@@ -164,14 +164,11 @@

         // Write out detectors
         
         for (Subdetector sub : getSubdetectors().values())

-        {
-        	//System.out.println("proc " + sub.getName() + " ...");
-        	

+        {        	

             SensitiveDetector sens = null;
             Readout readout = sub.getReadout();
             if (readout != null)

-            {
-                

+            {                

                 if (sub.isTracker())
                 {
                     sens = new Tracker(sub.getName());

@@ -190,8 +187,15 @@

                 
                 if (sub.isCalorimeter())
                 {

-                    LCDDSegmentation seg = (LCDDSegmentation) readout.getSegmentation();
-                    seg.setSegmentation((Calorimeter) sens);

+                	try 
+                	{
+                		LCDDSegmentation seg = (LCDDSegmentation) readout.getSegmentation();
+                		seg.setSegmentation((Calorimeter) sens);
+                	}
+                	catch (Throwable x)
+                	{
+                		throw new RuntimeException("Readout " + readout.getName() + " is not a valid Segmentation object.", x);
+                	}                	                    

                 }
             }