Index: trunk/ppSub/src/ppSubReadout.c
===================================================================
--- trunk/ppSub/src/ppSubReadout.c	(revision 14495)
+++ trunk/ppSub/src/ppSubReadout.c	(revision 14516)
@@ -92,5 +92,5 @@
 
     // Mask for subtraction
-    psImage *subMask = pmSubtractionMask(inRO->mask, refRO->mask, maskBad, size, footprint);
+    psImage *subMask = pmSubtractionMask(refRO->mask, inRO->mask, maskBad, size, footprint);
 
     memCheck("mask");