Index: trunk/ppStack/src/ppStackCombinePrepare.c
===================================================================
--- trunk/ppStack/src/ppStackCombinePrepare.c	(revision 34854)
+++ trunk/ppStack/src/ppStackCombinePrepare.c	(revision 34859)
@@ -34,10 +34,13 @@
 /*       options->expRO = NULL; */
 /*     } */
-    pmCell *bkgCell;
-    int bkg_r0,bkg_c0;
-    int bkg_nC,bkg_nR;
+    int bkg_r0 = 0,bkg_c0 = 0;
+    int bkg_nC = 0,bkg_nR = 0;
     if (bkgName) {
       ppStackFileActivationSingle(config, PPSTACK_FILES_BKG, true, 0);
       pmFPAfile *file = pmFPAfileSelectSingle(config->files, "PPSTACK.INPUT.BKGMODEL", 0);
+      if (!file)  {
+        psError(PPSTACK_ERR_ARGUMENTS, false, "Output background model selected but no inputs provided.");
+        return false;
+      }
       pmFPAview *view = ppStackFilesIterateDown(config);
       pmReadout *ro = pmFPAviewThisReadout(view,file->fpa);
@@ -47,5 +50,5 @@
       bkg_nC = ro->image->numCols;
       bkg_nR = ro->image->numRows;
-      bkgCell = pmFPAfileThisCell(config->files, view, bkgName); // Bkg cell
+      pmCell *bkgCell = pmFPAfileThisCell(config->files, view, bkgName); // Bkg cell
       
       options->bkgRO = pmReadoutAlloc(bkgCell); // BKG readout