Index: /trunk/ppSub/src/ppSubCamera.c
===================================================================
--- /trunk/ppSub/src/ppSubCamera.c	(revision 23298)
+++ /trunk/ppSub/src/ppSubCamera.c	(revision 23299)
@@ -218,5 +218,8 @@
     // Output subtraction kernel
     pmFPAfile *kernel = defineCalcFile(config, output, "PPSUB.OUTPUT.KERNELS", PM_FPA_FILE_SUBKERNEL);
-
+    if (!kernel) {
+        psError(PS_ERR_UNEXPECTED_NULL, false, "Unable to define file PPSUB.OUTPUT.KERNELS");
+        return false;
+    }
 
     psMetadata *recipe = psMetadataLookupMetadata(NULL, config->recipes, PPSUB_RECIPE); // Recipe for ppSim