Index: trunk/ppTranslate/src/ppMopsMerge.c
===================================================================
--- trunk/ppTranslate/src/ppMopsMerge.c	(revision 28623)
+++ trunk/ppTranslate/src/ppMopsMerge.c	(revision 30532)
@@ -35,5 +35,5 @@
 
     ppMopsDetections *merged = NULL;    // Merged list
-    int num = 1;                                                         // Number of merged files
+    int num = 0;                                                         // Number of merged files
     for (int i = 0; i < detections->n; i++) {
         ppMopsDetections *det = detections->data[i]; // Detections of interest
@@ -163,4 +163,9 @@
     }
 
+    if (num == 0) {
+    	//All detections were NULL?!
+	psTrace("ppMops.merge", 3, "All %d detections were NULL\n", detections->n);
+    	return NULL;
+    }
     psTrace("ppMops.merge", 2, "%ld sources in merged detections list\n", merged->num);