Index: /trunk/psModules/src/imcombine/pmSubtractionMatch.c
===================================================================
--- /trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 26979)
+++ /trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 26980)
@@ -594,5 +594,5 @@
             // generate the window function from the set of stamps
             if (!pmSubtractionStampsGetWindow(stamps, size)) {
-                psError(PS_ERR_UNKNOWN, false, "Unable to get stamp window.");
+                psError(psErrorCodeLast(), false, "Unable to get stamp window.");
                 goto MATCH_ERROR;
             }
Index: /trunk/psModules/src/imcombine/pmSubtractionStamps.c
===================================================================
--- /trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 26979)
+++ /trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 26980)
@@ -725,5 +725,5 @@
     psTrace("psModules.imcombine", 3, "Normalisation window radius set to %d\n", stamps->normWindow);
     if (stamps->normWindow == 0 || stamps->normWindow >= size) {
-        psError(PS_ERR_UNKNOWN, true, "Unable to determine normalisation window size.");
+        psError(PM_ERR_STAMPS, true, "Unable to determine normalisation window size.");
         return false;
     }