diff --git a/gtk2_ardour/mixer_ui.cc b/gtk2_ardour/mixer_ui.cc
index 9d918d4e3b..40735a0635 100644
--- a/gtk2_ardour/mixer_ui.cc
+++ b/gtk2_ardour/mixer_ui.cc
@@ -393,6 +393,10 @@ Mixer_UI::sync_order_keys (string const & src)
 		unsigned int old_key = order;
 		unsigned int new_key = route->order_key (N_("signal"));
 
+		cerr << route->name() << " old was " << order << " new is " << new_key << " exists ?"
+		     << (keys.find (new_key) != keys.end())
+		     << endl;
+
 		keys[new_key] = old_key;
 
 		if (new_key != old_key) {