Index: trunk/ppSub/src/ppSubReadout.c
===================================================================
--- trunk/ppSub/src/ppSubReadout.c	(revision 14847)
+++ trunk/ppSub/src/ppSubReadout.c	(revision 14873)
@@ -84,5 +84,8 @@
     }
 
-    psArray *sources = psMetadataLookupPtr(&mdok, sourcesRO->analysis, "PSPHOT.SOURCES"); // Sources in image
+    psArray *sources = NULL;            // Sources in image
+    if (sourcesRO) {
+        sources = psMetadataLookupPtr(&mdok, sourcesRO->analysis, "PSPHOT.SOURCES");
+    }
 
     if (!pmSubtractionMatch(outRO, refRO, inRO, footprint, regionSize, spacing, threshold, sources,