Index: trunk/psModules/src/imcombine/pmSubtraction.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtraction.c	(revision 15449)
+++ trunk/psModules/src/imcombine/pmSubtraction.c	(revision 15455)
@@ -4,6 +4,6 @@
  *  @author GLG, MHPCC
  *
- *  @version $Revision: 1.72 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-11-03 02:28:24 $
+ *  @version $Revision: 1.73 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-11-05 23:43:38 $
  *
  *  Copyright 2004-2007 Institute for Astronomy, University of Hawaii
@@ -1217,11 +1217,13 @@
         PS_ASSERT_IMAGES_SIZE_EQUAL(ro1->weight, ro1->image, false);
     }
-    PS_ASSERT_PTR_NON_NULL(ro2, false);
-    PS_ASSERT_IMAGE_NON_NULL(ro2->image, false);
-    PS_ASSERT_IMAGE_TYPE(ro2->image, PS_TYPE_F32, false);
-    if (ro2->weight) {
-        PS_ASSERT_IMAGE_NON_NULL(ro2->weight, false);
-        PS_ASSERT_IMAGE_TYPE(ro2->weight, PS_TYPE_F32, false);
-        PS_ASSERT_IMAGES_SIZE_EQUAL(ro2->weight, ro1->image, false);
+    if (mode != PM_SUBTRACTION_MODE_1) {
+        PS_ASSERT_PTR_NON_NULL(ro2, false);
+        PS_ASSERT_IMAGE_NON_NULL(ro2->image, false);
+        PS_ASSERT_IMAGE_TYPE(ro2->image, PS_TYPE_F32, false);
+        if (ro2->weight) {
+            PS_ASSERT_IMAGE_NON_NULL(ro2->weight, false);
+            PS_ASSERT_IMAGE_TYPE(ro2->weight, PS_TYPE_F32, false);
+            PS_ASSERT_IMAGES_SIZE_EQUAL(ro2->weight, ro1->image, false);
+        }
     }
     if (subMask) {