Index: trunk/ppImage/src/ppImageDetrendReadout.c
===================================================================
--- trunk/ppImage/src/ppImageDetrendReadout.c	(revision 23411)
+++ trunk/ppImage/src/ppImageDetrendReadout.c	(revision 23426)
@@ -143,4 +143,9 @@
 	// get normalization from the class_id
 	float norm = psMetadataLookupF32 (&mdok, normlist, classID);
+	if (!mdok) {
+	    psError(PS_ERR_IO, false, "failed to find class ID %s in normalization table\n", classID);
+	    psFree(detview);
+	    return false;
+	}
 
         pmHDU *hdu = pmHDUFromReadout(input); // HDU of interest