Index: trunk/ppMerge/src/ppMergeLoop.c
===================================================================
--- trunk/ppMerge/src/ppMergeLoop.c	(revision 17424)
+++ trunk/ppMerge/src/ppMergeLoop.c	(revision 18025)
@@ -306,15 +306,18 @@
             }
         }
-        psList *inChips = psListAlloc(NULL);
-        for (int i=0; i < numFiles; i++) {
-            pmChip *chip = pmFPAviewThisChip(view, ((pmFPAfile *)inputs->data[i])->fpa);
-            psListAdd(inChips, PS_LIST_TAIL, chip);
-        }
-        if (!pmConceptsAverageChips(outChip, inChips, true)) {
-            psError(PS_ERR_UNKNOWN, false, "Unable to average Chip concepts.");
+
+        if (outChip->data_exists) {
+            psList *inChips = psListAlloc(NULL);
+            for (int i=0; i < numFiles; i++) {
+                pmChip *chip = pmFPAviewThisChip(view, ((pmFPAfile *)inputs->data[i])->fpa);
+                psListAdd(inChips, PS_LIST_TAIL, chip);
+            }
+            if (!pmConceptsAverageChips(outChip, inChips, true)) {
+                psError(PS_ERR_UNKNOWN, false, "Unable to average Chip concepts.");
+                psFree(inChips);
+                goto ERROR;
+            }
             psFree(inChips);
-            goto ERROR;
-        }
-        psFree(inChips);
+        }
         if (!pmFPAfileIOChecks(config, view, PM_FPA_AFTER)) {
             goto ERROR;