Index: /trunk/psModules/src/concepts/pmConceptsRead.c
===================================================================
--- /trunk/psModules/src/concepts/pmConceptsRead.c	(revision 12621)
+++ /trunk/psModules/src/concepts/pmConceptsRead.c	(revision 12622)
@@ -304,6 +304,8 @@
                 psFree(nameSource);
                 if (mdok && strlen(source) && strcasecmp(source, "HEADER") == 0) {
-                    headerItem = psMetadataLookup(hduLow->header, conceptItem->data.V);
-                    if (!headerItem && hduHigh != hduLow) {
+                    if (hduLow->header) {
+                        headerItem = psMetadataLookup(hduLow->header, conceptItem->data.V);
+                    }
+                    if (!headerItem && hduHigh != hduLow && hduHigh->header)) {
                         headerItem = psMetadataLookup(hduHigh->header, conceptItem->data.V);
                     }
@@ -333,6 +335,8 @@
                     psList *values = psListAlloc(NULL); // List containing the values
                     while ((key = psListGetAndIncrement(keysIter))) {
-                        psMetadataItem *value = psMetadataLookup(hduLow->header, key);
-                        if (!value && hduHigh != hduLow) {
+                        if (hduLow->header) {
+                            psMetadataItem *value = psMetadataLookup(hduLow->header, key);
+                        }
+                        if (!value && hduHigh != hduLow && hduHigh->header) {
                             value = psMetadataLookup(hduHigh->header, key);
                         }