Index: trunk/ppStack/src/ppStackCamera.c
===================================================================
--- trunk/ppStack/src/ppStackCamera.c	(revision 14404)
+++ trunk/ppStack/src/ppStackCamera.c	(revision 14520)
@@ -40,6 +40,6 @@
         psString weight = psMetadataLookupStr(&mdok, input, "WEIGHT"); // Name of weight map
 
-        float seeing = psMetadataLookupF32(NULL, input, "SEEING"); // Seeing FWHM
-        if (isnan(seeing)) {
+        float seeing = psMetadataLookupF32(&mdok, input, "SEEING"); // Seeing FWHM
+        if (!mdok || isnan(seeing) || seeing == 0.0) {
             psError(PS_ERR_BAD_PARAMETER_VALUE, true, "Component %s lacks SEEING of type F32", item->name);
             psFree(iter);
@@ -47,6 +47,6 @@
         }
 
-        float weighting = psMetadataLookupF32(NULL, input, "WEIGHTING"); // Relative weighting
-        if (isnan(weighting)) {
+        float weighting = psMetadataLookupF32(&mdok, input, "WEIGHTING"); // Relative weighting
+        if (!mdok || isnan(weighting) || weighting == 0.0) {
             psError(PS_ERR_BAD_PARAMETER_VALUE, true, "Component %s lacks WEIGHTING of type F32", item->name);
             psFree(iter);
@@ -54,6 +54,6 @@
         }
 
-        float scale = psMetadataLookupF32(NULL, input, "SCALE"); // Relative scale
-        if (isnan(scale)) {
+        float scale = psMetadataLookupF32(&mdok, input, "SCALE"); // Relative scale
+        if (!mdok || isnan(scale) || scale == 0.0) {
             psError(PS_ERR_BAD_PARAMETER_VALUE, true, "Component %s lacks SCALE of type F32", item->name);
             psFree(iter);