Index: trunk/ppStack/src/ppStackMatch.c
===================================================================
--- trunk/ppStack/src/ppStackMatch.c	(revision 18183)
+++ trunk/ppStack/src/ppStackMatch.c	(revision 18184)
@@ -128,5 +128,5 @@
         // Set the variance factor
         float vfNew = psMetadataLookupF32(NULL, output->analysis, PM_SUBTRACTION_ANALYSIS_VARFACTOR);
-        float vfOld = psMetadataLookupF32(NULL, readout->concepts, "CELL.VARFACTOR");
+        float vfOld = psMetadataLookupF32(NULL, readout->parent->concepts, "CELL.VARFACTOR");
         if (isfinite(vfOld)) {
             vfNew *= vfOld;