Index: /trunk/ppMerge/src/ppMergeCombine.c
===================================================================
--- /trunk/ppMerge/src/ppMergeCombine.c	(revision 13768)
+++ /trunk/ppMerge/src/ppMergeCombine.c	(revision 13769)
@@ -162,5 +162,11 @@
 
                     // Only reading and writing the first readout in each cell (plane 0)
-                    if (pmReadoutReadNext(stack->data[i], fits, 0, options->rows)) {
+		    bool readOK;
+                    if (pmReadoutReadNext(&readOK, stack->data[i], fits, 0, options->rows)) {
+			if (!readOK) {
+			    psError(PS_ERR_IO, false, "Failed to read concepts for cell.\n");
+			    psErrorStackPrint(stderr, "trouble reading data!\n");
+			    exit (1);
+			}
                         // If we're creating a bias or a dark, we don't want to generate a mask
                         if ((options->zero || options->scale || options->shutter || options->mask) &&