Index: gcode.c
===================================================================
--- gcode.c	(revision 29222)
+++ gcode.c	(revision 29223)
@@ -363,7 +363,7 @@
 
 	if (pcb_cam_end(&gctx.cam) == 0)
 		if (!gctx.cam.okempty)
-			pcb_message(PCB_MSG_ERROR, "gcode cam export for '%s' failed to produce any content\n", options[HA_cam].str);
+			pcb_message(PCB_MSG_ERROR, "gcode cam export for '%s' failed to produce any content (layer group missing)\n", options[HA_cam].str);
 }
 
 static int gcode_parse_arguments(pcb_hid_t *hid, int *argc, char ***argv)