Index: trunk/psModules/src/imcombine/pmStack.c
===================================================================
--- trunk/psModules/src/imcombine/pmStack.c	(revision 13495)
+++ trunk/psModules/src/imcombine/pmStack.c	(revision 13520)
@@ -8,6 +8,6 @@
  *  @author GLG, MHPCC
  *
- *  @version $Revision: 1.4 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2007-05-24 02:13:17 $
+ *  @version $Revision: 1.5 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2007-05-25 03:43:22 $
  *
  *  Copyright 2004-2007 Institute for Astronomy, University of Hawaii
@@ -104,4 +104,5 @@
 
     // Extract the pixel and mask data
+    int numBad = 0;                     // Number of bad pixels
     for (int i = 0; i < num; i++) {
         pmStackData *data = inputs->data[i]; // Stack data of interest
@@ -110,5 +111,15 @@
         pixelData->data.F32[i] = image->data.F32[y][x];
         pixelMasks->data.PS_TYPE_MASK_DATA[i] = mask->data.PS_TYPE_MASK_DATA[y][x];
-    }
+        if (pixelMasks->data.PS_TYPE_MASK_DATA[i] & maskVal) {
+            numBad++;
+        }
+    }
+    if (numBad == num) {
+        // Catch the case where everything is masked
+        image->data.F32[y][x] = NAN;
+        mask->data.PS_TYPE_MASK_DATA[y][x] = bad;
+        return false;
+    }
+
     if (reject) {
         for (int i = 0; i < reject->n; i++) {